beginning of 2022, hosted by the Soas Middle East Institute and co-hosted by the Center for Palestine Studies and the Center for Iranian Studies. I'm really delighted to welcome Dr. Marina Rasto from Princeton University. And she's going to talk about her book, Lost Archive, which is an archive of the 30-mide caliphate, 1909 to 1171, how it survived in an unexpected place, the storage room, or the Geniza. I don't know whether I'm pronouncing it properly. Office synagogue in Cairo, recycled as scrap paper and deposited that by medieval Jews. She tells the story of this extraordinary client inviting us to reconsider the longstanding of the mistaken consensus that before 1500, the dynasties of the Islamic Middle East produced few documents and preserved even fewer. I don't want to take too much of your time, but I want to introduce Marina. Marina is the Keduri Zilka Professor of Jewish Civilization in the Near East and Professor of Near Eastern Studies and History at Princeton University. She is director of the Princeton Geniza Lab and the MacArthur Fellow and is the author of heresy and the politics of community. The Jews of the 30-mide caliphate. Without further ado, I invite Marina to begin her talk. She is going to share a PowerPoint with us. And as normal, please post your questions in the chat icon at the bottom of the Zoom page. And I will collect the questions and pose them to Marina at the end of the discussion. But I also want to welcome Nargis Fersat, who is the chair of the Center for Iranian Study, who is my partner in crime, and really looking forward to the discussion. Marina, over to you. Thank you so much. Thank you, Dina, and thank you, Nargis, and thanks to everyone who made this possible. It's really an honor to be here among you. The very first foray I did into the subject of this book before I knew I was even writing this book was an article published in the Bulletin of the Sohas in 2010. So this feels full circle to me. So thank you so much. So I'm going to start with the cover of the book. I just want to point out a few things about it and why I chose this as the color illustration. So this comes from a larger illustration that actually has two angels, not just the one that appears on the cover of the book. And this is what the page looks like in its original context. It's an illustration from a 13th century Iraqi manuscript, even though the book is neither about the 13th century nor really about Iraq, although as you'll see, I do get into Iraq a little bit. It's mainly about Egypt in the 10th, 11th, and 12th centuries. But the illustration was too tempting because in addition to the fantastic robes and the golden tiras bands that you can see on the shoulders of these fantastic robes, each of these angels is depicted holding a long scroll. Erotolus is the technical term that manuscript scholars use for a long role, a vertical scroll written with very, very wide line spacing in Arabic script. And anyone in the medieval Islamic world would immediately recognize such a Erotolus as being a government decree because this by the 13th century was how government decrees had come to look very, very profligately spaced, rotally that were quite performative and grand to look at. The context, I just want to give you a sense of the historical context before I kind of get into the native gritty, is this interesting moment in the history of the Middle East when the Abbasid Caliphate, which had ruled over most of the Islamic world for a couple of centuries began to fragment into smaller caliphates, smaller polities that then declared themselves caliphates also, which was really an affront to the political theory of the caliphate. There was only supposed to be one caliph at a time, the vice-gerent of God on earth. And by the middle of the 10th century, in fact, there are three caliphates. There's one in Spain, the Umayyad Caliphs. They declare themselves caliphs in 929 and the Fatimids who arose in central North Africa and declared their caliphate in 909. So this map shows Fatimid territory in the early 10th century. And if you keep your eyes on the map, you can see what happens over the course of the 10th century. Fatimid territory goes from being this little bit of Northern Africa to being quite extensive and really covering the whole of the Southern Eastern Mediterranean. So if you were a 10th century Mediterranean person, the Fatimids would be like the central power that you're aware of and that you have to contend with in whatever you do. And meanwhile, the Abbasids were restricted to what to them must have seemed like a very, very small area compared to what they ruled before. The Fatimids entered Egypt in 969. So that's kind of the key date for Egypt. It was a bloodless conquest. In fact, Egypt had been in a political vacuum for a while. The Abbasids actually found it difficult to govern territory so far afield. But Egypt was a very big prize for the Fatimids because it was a very lucrative tax-generating region. And so once the Fatimids had secured Egypt, that was kind of, you know, that solidified their empire and they continued to rule through 1171, although they lost crucial parts of Syria because of their crusades. But they were in Egypt until 1171 and that's when the regime fell. And the regime that succeeded them were the Ayyubids most famous for Saladin, who's the one who gets Jerusalem back from the crusaders in 1187. The people who lived through this would have been quite aware of what was happening. So there was a geographer who was from Jerusalem who lived in the late 10th century, who in his survey of all the countries of the world that he knew of says about Egypt and Cairo in particular, Baghdad has been superseded until the day of judgment. Egypt's metropolis has now become the greatest glory of the Muslims. So people in the 10th century would have been even aware that the center cultural, political, economic had shifted from Baghdad to Cairo. The city of Cairo was in fact founded by the Fatimids. So as soon as the Fatimids entered Egypt in 969, they set about building a palace. So Cairo was initially just a Palatine complex.  The place where normal people lived was to the south here, Fusat, which was an older city founded on a Roman fortress of which you can still see some of the remains here in black. If you visit Cairo today and you can actually visit the segment of the city that used to be known as Fusat, you should ask for Coptic Cairo or Missila Padima. And the yellow buildings that you see here are churches that still exist. The green ones are mosques. And in the blue here, you have the Benazir Synagogue. The Benazir Synagogue was built in the 11th century and it preserved an enormous number of manuscripts in a kind of secret chamber. So many manuscripts in fact, that I mean less than half I think have been catalogued or identified in any way at this point. This is a view from the interior of the Benazir Synagogue. You're in the mezzanine looking towards the front wall of the synagogue. And if your eye follows along the left-hand side of the mezzanine toward the front wall, you'll see that there's a tiny opening here. So this isn't the original synagogue. It was completely rebuilt in the late 19th century, which has to do with the fact that these manuscripts were discovered. They wouldn't have been discovered had this synagogue not been completely torn down and then rebuilt. But it was in a kind of walled in chamber much like this one that the Ghaniza manuscripts were found. They were in absolutely no order whatsoever. You cannot even do stratigraphy on Ghaniza finds, unfortunately. So it really is just a jumble of texts ranging in date from about 900. There are some early, early outliers that are that early. Mostly things pick up in about 1,000 up until 1897, which is when the synagogue chamber was finally emptied. The name Ghaniza comes from Bait Ghaniza, which is a kind of traditional storage chamber for worn texts in Hebrew script. But what's so interesting as we kind of go deeper and deeper into the material that was found there is that probably the in Hebrew script part needs to be taken out of the definition. I mean, that's kind of like what we tell our students, but is it really true? I think that that can be questioned. And just to give you a kind of very, very brief overview of the bigger picture of what's in the Ghaniza before I get to the little piece of it that generated my book. The vast majority of what's been found in the Ghaniza dates to between 950 and 1250, although there are significant pockets from the 16th and 19th centuries. And this has to do with the urban demography of Cairo and kind of the neighborhoods that Jews inhabited in one period or another. The grand total is about 400,000 pages of text or fragments of pages. And most of the pages found in the Ghaniza are single pages, even if they come from larger works. So things were very kind of tattered. And if you had a whole book, you probably wouldn't put it in the Ghaniza, you would repair it or try and keep it intact in some way. But it was when things really became too worn to be useful that they entered the Ghaniza chamber. So about 90% of what was found in the Ghaniza, again, an estimate because we don't exactly know what all is in there. About 90% of it are books. And I put books in quotation marks because books in the Middle Ages could be many different formats. The Codex, which is like the book as we know it, what you bring to the beach with you, that's a Codex for medievalists, but not all books in the Middle Ages were Codeses. That leaves about 10% of the material that is documentary. So, documentary texts being letters, legal deeds, lists, accounts, ephemera of every possible type. And that is what I've always worked on. I mean, since I got into this business. However, I was trained to work on the documentary texts in Hebrew script. And for this project, I made a kind of turn towards the documentary texts in Arabic script. And there were many, many more than I expected at the beginning. So here I'm just showing you a kind of typical example of a document in Hebrew script. This is a marriage contract. It's in the Hebrew script and the Hebrew language. Whereas a lot of texts that you find in Hebrew script are in Aramaic or in Jidao Arabic, which is Arabic in Hebrew characters. And in fact, here is an example of a Jidao Arabic text. This is a letter. It's a personal letter, personal slash business. They're often mixed from a trader who is at the time of writing traveling down the Red Sea towards the Indian Ocean where he's going to be trading. There was a burgeoning Indian Ocean trade in the 12th and 13th century that's documented in trade letters from the Geniza. So that is what we kind of know of the Cairo Geniza in general. It covers this enormous swath of the globe. You have Jews who are trading all across the Indian Ocean and then certainly material from all over the Mediterranean. So it's really quite a remarkable cash of texts. The discovery stories are quite interesting. A book from 10 years ago, Sacred Trash tells the story of how the Geniza was ultimately, how it came to the attention of scholars. And a book that is coming out next month by Rebecca Jefferson, the Pyro Geniza and the Age of Discovery in Egypt. Calls into question some aspects of the story that's told in the first book, but both are absolutely fantastic. Attempts to reconstruct how all this came about and what led to the Geniza discovery and where did all the manuscripts go? Questions like that that can be very difficult to nail down. So far we have two books on that. Part of the reason that tracking the Geniza is so difficult is that ultimately the texts were dispersed across more than 60 libraries and private collections. The vast majority is at the Cambridge University Library and their significant collections in New York, St. Petersburg, Oxford, Manchester and London in addition to a smattering of other places. Which means that you can be looking at a single text that can be divided by an ocean. So when you find two puzzle pieces like this, it's called a join.  So this is a join between manuscripts in New York and Oxford. Digital imaging has made it much, much more, much easier to find these joined because you can be in two libraries at the same time as it were. You don't have to rely on your visual memory or difficult access to photographs. Here's another example of a join. These are two pieces that are in Cambridge and this is a 15th century court record from Cairo. And what's so frustrating when I tell my students is that if you find a join and they're both in Cambridge, it doesn't mean that they're gonna be recatalogued and housed together. On the contrary, these will always bear these two totally different class marks and then in the literature they're referred to with a plus sign in between the two class marks. So the record of the join is always is there to see for posterity. Okay, so that leads me into the heart of the matter. This is a very, very impressive join which I myself did not find. This was found by Rone Shueika and it's impressive because it's in many, many pieces. From my point of view, this is an incredibly precious text because this is about a meter, 23 centimeters of a Fatimid decree. And Fatimid decrees until this came along and fell into my lap were, there were 10 of them that were known in the world, eight of which had been preserved at the monastery of St. Catherine in Sinai and two of which were in Cairo and they had been published in the 1960s and as far as anybody knew that was it. But it turns out that there were lots and lots of fragments of Fatimid decrees in the Geniza. And so the reason I undertook the lost archive was to try to explain or understand why. One of the reasons that I could never have found this join myself is that you can see immediately you have Arabic script with very wide line spacing, right? So even if I hadn't told you that this is a decree just looking at the cover of my book and what I told you about it, you'd know that this was a decree but the very wide line spacing makes it virtually impossible to put the puzzle pieces together because you don't have the text kind of telling you what goes with what. And often with these joins, they're not perfect puzzle pieces because fragments decay from the edges inward. So the reason that my colleague Ronny Shueka was able to find this is that he was looking for a completely different text. He was looking for the Hebrew and Aramaic text on the other side. And he found 120 examples of this text in the Geniza and he realized that these belong together in a single manuscript. He then emailed me. I think we were in Oxford at the time and he emails me from across the Oriental Institute Library and says, hey, I found something that you might be interested in. And not only was I interested, I actually told him who the scribe was on this side on the Verso, the side that he was interested in. A man named Ephraim Ben-Shemaria who was the head of the congregation that prayed in the Ben Ezra synagogue where all of this was found. And this is like people who work on literary texts in the Geniza as Ronny Shueka does versus people like me who work on documentary texts. We don't talk enough. And this was an example of that where one of my documentary guys happened to be the scribe of one of his literary manuscripts. So he said, look at the other side. And I did. And I said, my gosh, like I have found lots of fragments of Fatima decrees but I've never been able to actually piece one together at quite this length before. So that was pretty much all the inducement I needed to try and follow through on this topic. One of the reasons it's so unusual and so exciting to find Fatima decree fragments in anywhere is that most of what we know about the Fatimids is based on long form sources, what historians would call literary sources. So not necessarily literature proper. They can also be chronicles or legal codes, anything written in long form, as opposed to a documentary text, anything intended for posterity. A historian would call a literary text. So this is one of the major sources that had been relied upon for Fatima history by a wonderful 15th century historian called the Macrizi who himself was from Cairo and spent his whole life in Cairo and was really just like hiring to his soul. And was so interested in Cairo that he wanted to know the history of the city including its founders, its founders being the Fatimids. So he wrote two books that have very, very significant information for the Fatimid period. Long form texts are very nice to work with because they have a narrative and they have a point of view which is not necessarily a weakness provided that you don't take their point of view at face value. They're also useful because in Macrizi for instance had access to earlier chronicles, earlier manuscripts that we no longer have. So often you can find information in these guys that's much, much older. So there are some 11th and 12th century eyewitness chronicles that are preserved in Macrizi's later chronicle of the Fatimids. But there are also things that chronicles can't give you. They can't give you the materiality of archival sources. The materiality itself contains information that can be important. The chronicles don't give you the messiness of a ground level view or as a historian they don't always give you the thrill of reconstructing history from fragments. Chronicles have a kind of deformation profession which is that they persuade you that they're telling the whole story. Not persuading you necessarily in so many words or explicitly, but the fact of having a coherent narrative is itself a kind of filter as any practicing historian will tell you. So archival documents can give you some of what chronicles can't, but archives on the other hand are a more elusive thing than one might think. The Geniza was not an archive. Archives are intended not just for storage but also for retrieval. Archives are organized spaces. There should be some sense of order. Otherwise the retrieval part of their mission simply can't work. Whereas for the Geniza, they were never intended for retrieval. But archives aren't always ready made. Sometimes you have to piece together your own archive from fragments. So if an archive hasn't survived in continuity down to the present but lies buried in some ruin or some secret chamber, then chances are it's going to be quite disorganized. And yet the fact remains that for the period before about 1100, the Middle East preserved more original documents than Europe, probably by an order of magnitude. So let me just explain what I mean by that. In Europe, most of the original documents that we have date from after 1100 for a very simple reason, which is there was a kind of bottleneck where many of the older documents were recopied into cartilaries. A cartilary being usually a codex-shaped book that preserves summaries of earlier documents. So a cartilary too will not give you the original kind of texture or material flavor of a document. Whereas from the Middle East, you have papayri from Egypt that date to just a decade after or maybe a few years after the Islamic conquest of Egypt in 640. However, the documentation is very, very Egypt-centric, very Egypt-heavy. So that's one thing that all documentary historians of the Middle East have to contend with. Okay, so as for Fatimid documents in the Cairo Geniza, there were many, many more of them than I anticipated. This is kind of a funny story for me because when I first started to work on this, I published a small kind of notice, a little article in the newsletter of the Cambridge University Library Geniza Research Unit saying kind of what these were and the fact that I was working on them and I started to get emails from people who had seen these widely spaced lines of Arabic in texts that they had worked on and not known what they were. So this was the very first email I got from a fantastic scholar called Shama Friedman who works on manuscripts of the Babylonian Talmud, one of the major works of Judaism from late antiquity. And he wrote to me and he said, now I understand why this manuscript that I published in the 1980s has these giant lines of Arabic going across it because in fact what it preserves is the end of what I believe to be a late fob in the decree but here I'm going based on paleography because there's no date on the fragment itself. That scribe, this one, sorry, this scribe has reused the text by chopping it into pieces or perhaps buying it already chopped up and then turning it 90 degrees and folding it in half to form a bifolio. There may be others just like it that were the other bifolios that belong in a single choir but those have not yet come to light. But there are many other ways of treating these fragmentary font in the decrees. So here's one that's cut in half down the middle. The scribe used it only on the other side which I'm not showing you. Here's one where the scribe wrote on the other side and didn't have enough room on the other side. So he started to write between the lines, quite literally between the lines but perpendicular. Here's one where you'll find the verse are totally covered but also again between the lines the scribe has taken some notes on the calendar as it turns out. Here the scribe has folded the page in quadrants and written a long incomium to a Fatima general an incomium in Hebrew. Not actually atypical from the kinds of things that you find in the Geniza. And here we have a page from a choir part of which was composed of recycled Fatima decrees. Some of these are quite large some of them are a bit smaller. There's no kind of one standard size but there are probably two more or less standard sizes that I was able to find 43 centimeters across and then 20 to 25 centimeters. And with the lengths, they could be enormously long. The longest Fatima decree, extant Fatima decree I'm aware of is more than eight meters long. I have not been able to reconstruct any thing of that length from Geniza fragments but there's plenty of quantity. Here are three different Fatima chancery decrees that were reused by a single Jewish trader and the significance of these fragments is that they were the first time I had actually been able to date both the original Fatima decree and also their reuse. So this gave me a clue to how long did it take for these things to get recycled? Which then was in turn a clue to how did they get recycled? So the Fatima decree has to date to after 1131 because a Caliph is mentioned who ascends to the Caliphate in 1131 and half of it. And the Jewish trader who reuses them actually mentions the date when he's writing his letters and that is 1139 and 1140. So we know that there's less than a decade between the reuse of at least some of these decrees between when they were originally issued and their reuse. And I'll get back to that question of the life cycle in just a minute. But first I wanna point out that it wasn't just Jews who reused Fatima decrees. This is a Christian reuse. So it's a text in Greek. This is found by my colleague Naim Fentihem and definitely a Fatima decree originally on Erecto. This is a Fatimid probably treaty with one of the Italian city-states, probably Genova, reused by a notary for a number of copies of legal texts in Latin. And so you can see the large lines which he's crossed out are in both Arabic and in Latin as well. And this is from more or less the same period, 1150s, 1160s. Part of the reason that nobody had worked on these before is simply that nobody knew what they were. So if you look in the 1906 otherwise fantastic catalog of the Bodleian Geniza collection, every time you find one of these documents it's catalog the same way which is scribbling. And in fact, scribbling is what people thought they were and what I certainly would have thought they were had Jeffrey Khan whose religious professor of Hebrew at Cambridge had he not come along and worked on texts like this one, like the ones that I worked on back in the 1980s and 1990s. And without his work, I would certainly not have been able to do mine. It's a practice also that goes beyond the Fatimids. So this is a 14th century decree from Egypt, the Mamluk sultans are the ones who issued this one reused by El-Maqrizi the historian that I mentioned earlier. So El-Maqrizi himself was not only aware of the practice of recycling decrees, he himself actually did it. Maqrizi also mentions a scenario where there was an attempted coup on the palace in Cairo during the Mamluk period, I think 1388 is the date that he's discussing during which the archives were, how shall we say liberated and sold off, he says, by weight on the market as scrap paper. So we know that there were sales of scrap paper at least in a later period. And I think it's not unlikely that those kinds of sales of scrap paper were also happening during the Fatimid period, although I have found no really like smoking guns, but there is sufficient circumstantial evidence that the practice was also an earlier one. It's also a practice, this recycling of decrees that transcends the Islamic world. So this was brought to my attention by Susan Whitfield, formerly of the British Library, director of the International Dunhuang Project at Dunhuang in Western China, where there was a kind of guineas-like thing that was found right around the same time, around 1900. You have the decree of one of the rulers of Dunhuang from the 10th century, giving an official permission to an official to send his daughter to a monastery, a Buddhist monastery, and this is reused on the verso for a Dharani, which is a kind of liturgical text in use among Buddhists. And fascinatingly, one of the most common reuses you have of the Fatimid decrees is liturgical as well. So when you saw a decree like this, you were meant to be impressed, but this was not the only format that decrees came in. And in fact, it wasn't the preferred format for archiving decrees if you were working in the Fatimid chancery or anywhere in the central administration. If you were an administrator, you would do something much more sensible. You would take something more compact. This is 25 centimeters across. So I've expanded it on the slides so that you can see it a bit closer up, but just to compare it to this one, sorry, I gave away the sunshine, to compare it to this one, this is 23 centimeters, sorry, 21 and a half centimeters across, whereas this one is 25 centimeters wide. So it is absolutely tiny compared to the Grand Rotally, which is as it should be, because if you're going to be archiving something, then space is at a premium and you wanna archive in as compact a way as you can. So this is a copy of a Fatimid decree. This time it's dated 1134, which is excellent for us. These things are rarely fully dated and often the date has been torn away. And it's been folded in half to form a bifolio. This bifolio, unlike some of the other ones that I've shown you, was not meant to be part of a choir or a codex. A bifolio was a kind of standard archival format and the way you would bind these things together in the archive was by punching them through with some kind of like a needle or a long nail. And in fact, you can see that each of these pages has a hole in the middle. Blue is the background that's used standardly at Cambridge when you photograph manuscripts. So that's the Cambridge blue back there, but these are holes right in the middle of the page. And that was a binding method for the archives. So it was Jeffrey Kahn who found this archival version of a Fatimid decree among the Ghaniza documents. And that was kind of, for me, that's what cracked open the case that, so what are these long, beautiful things for? They're to impress people. They're certainly not for preservation or archiving. Which raises the question, once you're finished reading the decree aloud or you as a lower official in Jerusalem receiving this decree from a higher official or from the central chancery in Cairo, once you've acted on its orders, what do you do with it? You're under no obligation to archive it because that's being done in the chancery in Cairo itself. So you can simply discard the paper. We're in a world of the handmade where people aren't simply throwing things away. Generally, things get reused until they can't be reused anymore. So any smart official would try to make some money on the side and use some of these perhaps to do that, selling them to use paper sellers from which or from whom anybody could buy them and reuse them. So in the book, this was maybe one of the crazier things that I did in the book, but I compared these rotally to the instruments of performance of, for instance, the who, right? Which is that once the performance has finished, the instruments will be destroyed, right? And that's kind of way of even heightening the excitement of the performance. They weren't necessarily destroyed in front of people the way that whose instruments were, but the idea is the same, that they're ephemeral instruments of performance. I think in the interest of time, well, let me just very briefly tell you what's on the slide, but I won't go through it in any detail. Towards the end of writing this book, so I turned in the manuscript in late 2018, I came into contact with a former PhD student from Princeton, Anna Dolganov, who is now at the University of Vienna, absolutely fantastic Roman historian and a paparologist who was working on very similar questions to mine, but a thousand years earlier, but also in Egypt. And she discovered that Romans were, had very different strategies of archiving from the Falkimids. And the strategies that the Romans used is that they wanted everything preserved in triplicate. They wanted preserved in the central archives, in the regional archives and the local archives, and they wanted it all to match and they basically have very high standards for record keeping, which sometimes backfired on them. So Dolganov found a papyrus originally from Teptunus in Middle Egypt that contains the complaints of archivists from the Arsinoite gnome, saying, we ourselves were appointed a very long time ago and have received from the previous keepers, documents, keepers of the archives, documents that for the most part lacked their beginning and some of which were generally damaged or stuck together while successive stratagoid and local scribes, royal scribes delivered to us their accounts and whatever state they were and due to the great quantity of the worlds, they lie unsorted in heaps. So translation, when we got our job, we found those piles lying around the archives being like nibbled up by mice on the floor. It's not our fault, it's the fault of the people before us, but now there's too much for us to fix ourselves. So can you please send us some help? So this kind of backlog of archiving is something that you would not find among Fatimid archivists. Fatimid archivists had the opposite approach. They did not wanna preserve things in triplicate. They were very, very lean. They pruned the archives often and they only archived exactly what they had to and generally speaking only in the central archives in Cairo. And we know this from some secondary descriptions from people like El Maltese about how the Fatimid's handled their archiving but also from the material remains of Fatimid archival texts themselves. Ultimately, I tried to argue in this book that the story isn't just about the Fatimids. It's also about the Abbasids and it's also it has implications for studying pre-modern states in general. The Abbasids, the relationship between the Fatimids and the Abbasids fascinates me because on the one hand, they hated each other and were enemies and the Fatimids wanted to reduce the size of the Abbasid caliphate to the point where they even almost debated Baghdad itself and the Fatimids were Shiites and the Abbasids were Sunnis which wasn't the only issue that divided them but was certainly part of it. And since there could only be one legitimate caliph there was no kind of neutral recognition treaty between these two empires. On the other hand, there is evidence of a very surprising kind of continuity in government administration techniques from the Abbasids over to the Fatimids and this was really fascinating to me. So there are three things that I track in my book that move from East to West. One of them is paper. The second is, sorry, I just have some kind of a glitch in my notes here. Yes, one of them is paper. One of them is Arabic calligraphy styles. Those also move from East to West. And the third is specific wording or ways of expressing imperial power through state documents. So I'll just give you a kind of glimpse of each of these things and then draw some conclusions. This is an Umayyad decree. The Umayyads ruled from 661 to 750. Their capital was in Damascus. So this is quite early as Arabic documents go and it's written on papyrus. So papyrus was a writing material that was available in abundance in Egypt. It had been used literally for millennia as the main portable writing surface among Egyptians. There were attempts to grow papyrus on the banks of the Tigris and also in Sicily. Nothing terribly long lived. So really, Egypt was kind of still the main producer in this period. This is a papyrus document that survives from Iraq. So one of the very, very rare medieval Arabic documents that survive from Iraq, this one was excavated at Samara which was an Abbasid palace in use in the 9th century. And I'll get back to the significance of this in a minute but for now I just wanted to show you an example of papyrus used outside of Egypt. Papyrus is a fascinating technology that ended up totally revolutionizing many aspects of Islamic culture. Papyrus making technology originated in China but it had been in use in Central Asia for many, many centuries when the Muslims got there in the early eighth century. So papyrus was like a totally normal writing surface in late antique Central Asia. Parchment was also used as well as tanned letter but paper was quite common. So when the Umayyads first got to Central Asia in the 720s they had their first encounter with paper and immediately started using it. The first Arabic documents that we have on paper are from Central Asia and they date from the 720s. This is the earliest dated, securely dated Arabic codex on paper. And it's from, actually that's not true. Sorry, there's another, there's an earlier one from the 9th century. Like I'll get back to what this is the earliest example of. In any case, this is a very early Abbasid manuscript on paper from the middle of the 10th century copied in Baghdad now in Istanbul. And then we have the Fatimid use of paper. By the time the Fatimids arrived in Egypt in 969 paper had been through many decades of being the kind of imperial writing surface of choice. The Abbasids heavily relied on paper for their day-to-day administration so that by the time Egyptians had access to paper starting in the 10th century it already had the prestige of the Abbasid government attached to it. What's remarkable that the story of paper in Egypt is that although papyrus had been used for millennia it had a very, very brief period of complete obsolescence by which I mean, sorry, that was badly phrased between 900 and 940, papyrus goes from being the writing surface of choice in Egypt to being totally obsolete. So between 900 and 940 paper takes over as the portable writing surface of choice among Egyptians despite the dominance of papyrus for many millennia beforehand and part of that very rapid obsolescence is the fact that paper came with governmental prestige attached to it because the Abbasids had relied on it for so long. So that's paper. Calligraphy also moves from east to west. That same Umayyad papyrus decree that I showed you, you can also see that it's very grand. There's wide line spacing and there's also wide space between the letters but this is a completely different kind of script. We refer to it as kufik script. It doesn't necessarily have to do with the city of Kufa but that's what it's called. And it's a very orthogonal script. So lots of horizontals, lots of verticals and lots of sharp angles. Eventually kufik script gets replaced by a curvilinear script. The Iraqi papyrus that I showed you has a kind of early example of curvilinear script which ultimately over just a few decades would turn into something like this. This is in fact to be the earliest securely dated example of a curvilinear proportioned script that we have and it dates from 959, 10 years before the Fatimid conquest of Egypt and the Fatimids exclusively used curvilinear proportioned script to write their government documents on paper, not on stone. They used other things for stone but for paper they used proportioned curvilinear script. And then the last thing that moves from east to west in my book are the specific ways of writing government documents in order to express the prestige of government. And fascinatingly the wording of these decrees turns out to in some sense be the most fungible. So formularies change very quickly, wording can change very quickly over time but it's the kind of substrates of how to write these government documents that change more slowly. And for me that's fascinating. I love that complexity that you're up against anytime you encounter two historical rivals, in this case the Abbas and the Fatimids but you can probably think of many other examples who are in fact quite similar even though they think they're totally different. So what Harold Luhn called the anxiety of influence means it's never just a polarized relationship. There will always be similarities. And as a historian it's absolutely fascinating to unravel those. So a couple of final words. What was I thinking when I started this project? Well, I thought I was writing a book on Fatimid petitions on the petition and response procedure among the Fatimid caliphs who would hear petitions on any subject didn't matter how minor or personal it was they encouraged their subjects to petition. And I thought that the Lost Archive was an introduction to the petitions book and when I got to, I don't know maybe like 100,000 words I realized this is no longer the introduction to a book this is a book of its own. I thought petitions were the most abundantly when I started the most abundantly preserved type of Fatimid document and the most important type for understanding the interface between the state and its subjects. That turned out not to be true. I thought that petitions were abundant because previous scholars had worked disproportionately on Fatimid petitions because they're very charismatic documents they have these little stories and they're kind of fun to unravel. But I also thought that petitions were the most important interface between the state and its subjects because previous scholarship had talked about the Fatimids as having ruled by petition and decree that there was this kind of passivity attributed to the Fatimids where they only issued a decree when somebody would petition them. That turned out not to be true. There were many, many, many Fatimid decrees that were issued without any petition to provoke them. And in fact, most of the decrees that I found from the Ghaniza were issued to lower officials from higher officials managing infrastructure, canals, taxes, crops all kinds of things that you do in the normal course of governance. What I, and also of course tax receipts were probably much much produced in much greater number than petitions were. So what I ended up with was a more realistic sense of how a medieval Middle Eastern state governed. There was a complex bureaucracy and the complexity lay not just in numbers but also in the complexity of procedures. It was also a principled government. The Fatimids actually had explicit statements to the effect of if we're going to be asking people for tax money and we don't want them to rebel or like totally hair guts, then we have to give them something in exchange and that's something that we wanna give them is justice. So in other words, the petitions were abundant. They weren't the most abundant thing but they were important in the Fatimid worldview because that had to do with the ethics of rule. And that in turn made me realize that the field had perhaps unconsciously internalized a vision of certain medieval Middle Eastern states that made them out to be simultaneously more and less powerful than they really were. So the previous vision of the Fatimids had overstated their power because the assumption was that the Fatimids like many pre-modern empires must have been autocratic. But in fact, for any pre-modern state there were real limits on autocracy because of practical constraints, communications, demographic constraints, right? The total population of the planet Earth in the year 1,100 was something like 300 million. So people are spread out very thinly compared to what we're used to. And also legitimacy concerns. There is a limit to how much you can sit on your subjects to extract resources from them without provoking rebellion. And then there's also this ethics of rule that I talked about. And previous visions of the Fatimids had, I mean, not just overstated their power but also understated their power or even elided it because they were focused on the central administration and less on the complexities of the provincial administration without which the central administration could not have done its job. So that is my book in a nutshell and I look forward to your questions. Thank you so much. That was quite fascinating and I learned a lot. So I do have a couple of kind of comments and questions. One of them wants to kind of go back to the significance of the cover if it's possible to talk about that again, just to refresh our minds. Sorry, the significance of? Of the cover, of the book cover. Oh, yes, of the book cover. So I found, I mean, I was kind of blown away by finding one of these decrees represented in an actual painting. But what was even kind of more fun about it is those aren't government officials that are holding these decrees, they're angels. This has to do with a Quranic verse that talks about the day of judgment when the good and bad deeds of man will be tallied up. So the angel on the right is tallying up the good deeds and on the left is tallying up the bad deeds. But interestingly, that kind of counting of good and bad deeds is reimagined by the artist as almost a bureaucratic procedure, right? And then the decree gets issued. So there are these angels with these decrees and they're kind of meant to be recognized as such, right? That's sort of the visual joke that's being made. I mean, maybe not a joke, but it's certainly a comment. There, I found one other really interesting set of illustrations from an early 14th century manuscript that had a Chancery scribe seated to the left-hand side of a ruler, actually a pre-Islamic ruler in this case, but depicted in the Islamic style from the 14th century. And fascinatingly, not only is the Chancery scribe writing on one of these rotally, but they're also copying from an archival decree with two holes in the middle and a string strung through. So this was like, you know, that was when the penny dropped about the whole kind of archiving system because people were aware of it and illustrated it in manuscript. Thank you. There's another question about the tale of Muayyad. Muayyad is believed to have a massive library. Would you have any comments about that or? So the Fatimid Library is really, a lot of ink has been spilled on this question. And part of it is that you will read in Fatimid Chronicles about the Chizan al-Qutb, the Treasury, right? The Imperial Treasury of Books. And part of it as well has to do with the way the Ayyubid takeover of the Fatimid caliphate has been depicted in the historiography, both medieval and modern historiography. So there's one chronicler who says that when Saladin abolished the Fatimid caliphate and declared loyalty once again to the Abbasids, he threw 1,600,000 volumes into the Nile until it ran black with ink, right? So my colleague Conrad Hirschler, who used to teach at your esteemed institution, was the first person who pointed out to me that whenever you see multiples of four and seven in the Chronicles, you have to ask yourself whether these numbers are real or not because they love multiples of four and seven. So what does that mean for the real Fatimid Library? Well, we certainly have many texts from the Fatimids, but the vast majority are in later copies. Copies made especially in Yemen and in Gujarat. Thank you. There's an interesting question by Muzna. First of all, thank you for the talk. Loads of the questions begin saying fascinating, riveting talk, et cetera. Does this combo of Arabic within Hebrew texts show the unity once lived in it or is simply due to the scarcity of writing material? Have you looked into that like kind of a social context or co-existence perhaps or? Absolutely. So co-existence in the sense in which we would imagine it today, right? In other words, for us, the idea that the vast majority of Jews lived in the Islamic world until something like 1200, 1300 is maybe paradoxical to us today because of 20th century politics. But in fact, at the time, there was absolutely nothing unusual about it. So the people I study from the Guineas of the Jewish traders, the Jewish communal servants, even like the nameless, I mean, nobody would have thought of this as coexistence. For them, it was just like completely normal. So Jews spoke Arabic, wrote Arabic, I mean, did it for Persian. They wrote it in Hebrew characters, but some didn't. Some switched back and forth between Hebrew and Arabic characters. And so yeah, I mean, this is like normal. That said, it's an interesting question of when like your average everyday person is looking at one of these recycled decrees, do they know what they're looking at? So this is a question I had a lot of fun thinking about because a colleague of mine, Oded Zinger, who is now teaching at the Hebrew University of Jerusalem, brought to my attention a Guineas of document that I knew about, and I had never really thought about it in this context. It's a record of a court case in which it's so great, but the testimony is a little story. And the story is we were walking past the market in a safe vein, which is a particular area in Cairo.  And we didn't know why.  And he was holding a piece of paper. And the piece of paper was a decree that said that he was allowed to leave the congregation that he belonged to and go and found his own congregation. So basically he had petitioned the Caleb and said, hey, I wanna found my own congregation, can I do that? And the chancellor was like, sure, why not? Like, we don't care what you do, that's fine. He'd gone above the head of his rabbi basically to say, I'm gonna defect. And in the testimony, the guys who passed him, all they had to do was take one look at this decree and they knew what they were looking at, right? So the more I thought about that, the more I thought, okay, this is like something that isn't just restricted to government offices, but something that people actually knew about. And in relation to the decrees, when you mentioned that the papers were sometimes recycled, was it just the actual paper or the contents? Like example, the decrees, were they also endorsed or do you know what happened to them? Were they... That's an excellent question. So in fact, there are many types of document in Hebrew scripts or Jewish documents that very clearly are imitating Fatimid chancery style. And this happens at different levels depending on the kind of document. But the clearest examples are the decrees and the petitions. There are documents in Hebrew issued by high ranking Jewish communal authorities. So the head of the Jewish community in Fustat or other kind of like important central figures in the community, when they issue pronouncements, starting in the 1060s, they begin to issue them with very, very wide line spacing. And also with a kind of upward curvature of the lines just like you have in the Fatimid decrees. And it's so striking that I wrote a whole article about it that I published in 2014. But interestingly, the Jewish iteration of this kind of wide line spacing decrees style did not begin under the Fatimids. It began in Baghdad. So in fact, it was Iraqi Jews who brought this kind of wide line spacing style over to the Fatimid realm and started to use it as a way of kind of expressing more power. And this is a more impressive looking degree and thus I'm a more impressive looking person if I issue it. With the petitions, it's even more fascinating because the petitions actually have the very wording of Fatimid petitions preserved in Judeo-Arabic. And in some cases, because it's formulaic, we can actually reconstruct holes in the Arabic Fatimid petitions based on what we find in the Judeo-Arabic and vice versa. So it's very much kind of one universe of a formulary that's getting passed back and forth. Yeah, thank you. So other questions related to whether the texts in Arabic was erased. One question says that the areas where Arabic texts is written within the Hebrew lines has sort of been erased. Is that correct? Whether you have any info on that or kind of your opinion? So of the hundreds, maybe more than a thousand of these things that I've looked at, I've only found one example where somebody tried to erase the Arabic text and they very quickly gave up because they realized they were destroying the paper. So parchment is often erased in the Middle Ages. First of all, because parchment is expensive, but also because you can scrape or rub the ink off of the surface of parchment and reuse it that way. That's what a palimpsest is, right? So the Greek word that gives us palimpsest means to scrape a new. So basically you're scraping ink off of the page to reuse it. You can't do that with paper. I mean, you can, but you end up with like very weak paper with holes in it, yeah. So that's why they end up writing around the lines as opposed to or between the lines as opposed to actually erasing the lines. I want to say one other thing about paper versus parchment. Parchment is very expensive. So you have the motivation to reuse it. So the question is if paper is inexpensive, then why are people reusing it? Was there a shortage? So I started to ask myself this question at some point when I started researching paper prices. And like one big caveat is that it's very, very difficult to research prices from documentary sources because the units of measure are not always standard. Often they're vague. Like they'll talk about a dust of paper, which is like a ream, but it doesn't actually have a fixed number the way our modern ream does. And there are all kinds of other measures. Then there's quality of paper. They talk about Syrian paper, Egyptian paper, paper named after this government official, paper named after that government official. But, and we have so much paper in the Geniza, but we can't correlate the names of these paper qualities with the actual paper that we're looking at. So that was one challenge. But once I kind of decided, okay, I'm just going to go with some vague like impressionistic numbers. What I discovered is that the only time people in the Geniza world actually write about a paper shortage is if their traders are writing from India. So India was a place where it was difficult to get your hands on paper. And in fact, we do have some Geniza documents from India written on cloth and basically like anything you can find. But for the rest, I have found no evidence that there was ever a shortage of paper in Egypt or Syria. I think it wasn't cheap, but it wasn't prohibitively expensive either. So why reuse? So that's why I said the thing that I mentioned earlier about like these are pre-modern cultures where everything is handmade. So you wouldn't even dream of throwing something away, right?  But back then you would reuse things in myriad ways until they were basically dust. And do you have any comments on the dispersal of suppose a dispersal of many part of my text by the agribeds when they came to power? Did they burn or throw the materials or just toss them away? Or did they preserve them somewhere? The question. That is, yeah. That's a very big and very important question. The Fatimid archives, where do they go? What happened to them? That is a question ultimately that I was unable to answer. But at the same time, it becomes a little bit easier to answer once you kind of divide the question into smaller chunks. So one very like interesting little rabbit hole that I went down that turned into chapters 11, 12 and 13 in the book was what happened to the Fatimid official manuals that were kind of kept around the bureaus of government as like guides to, you know, how do you actually do a cadastral survey in the Delta? That kind of thing. And those fascinatingly had remarkable longevity. So there was a particular Fatimid guide to taxation that gets copied and sorry, it's actually written in the IUBIT period, but it's written by an official trained under the Fatimids. We don't actually have a Fatimid one that survives over that period, but we do have officials who are trained under the Fatimids who continue to work under the IUBITs, practicing what we assume are similar methods to what they would have done under the Fatimids. So one of these early IUBIT taxation manuals is copied continuously until the Ottoman period, basically until the 19th century. That's like the latest manuscript we have of it. Because on very, very technical subjects, you would have been motivated to keep the instruction manual, you know, around as long as you could. But as far as these day to day government administrative documents go, we have many, many later copies in Mamluk-era Chronicles, in IUBIT-era Chronicles. But as far as the originals go, the two places, the only, well, it's like three places you can find them are the Monastery of St. Catherine and Sinai, the Cairo Geniza, and then another one of the synagogues in Cairo, which has now been incorporated into the Jewish Community Archives. It was the Carrite Synagogue, or one of the two Carrite Synagogues where they preserved an intact Ottoman decree from 1034. And so in relation to the documents, there's a question whether that, other than a chancellery or legal records, whether any liturgical or historical texts found in the Geniza archives. In Arabic script or Hebrew script? I doesn't say, but I would think it's the Hebrew script. The question doesn't look good. So yes. Well, I mean, I can answer both. So with the Hebrew script, the vast majority of what is, I mean, I don't wanna say the majority, but plurality, so about a quarter of what we have actually catalogued from the Geniza that we know about is liturgical. So it seems to have been the people who were leading services in the synagogue who had the most acute need for scrap paper. So they're the big recyclers. And part of that is that they were expected to come up with new liturgical poems, like all the time. So they were constantly, like rummaging around for used paper. As far as the Arabic script texts go, this is really an area of research that needs more people. There are an enormous number of Arabic script texts from the Geniza. I found many, many more in the course of this project than I could make use of. They're now being input into the Princeton Geniza Project database, which I run, and I have a fantastic team working with me. And one of the things that we're doing right now is inputting all of those Arabic script texts, which include Hadihor documents, a fantastic source for history, and as well as medical texts, alchemical texts, scientific texts, and government documents of many different varieties. And then philosophy, I mean, all the kinds of genres that were common in this period, Jews were reading them, and they were, in many cases, reading them in Arabic script. So just to give you an example, and this is actually something I have an image of in the book, we can actually trace, in part, the transmission of the Rasat-le-Huana Safa, the letters of the Brethren of Purity, this amazing 10th century Iraqi encyclopedic text written collectively by a group who, until recently had never been identified, but certainly written in Iraq and Basra and Baghdad. The reception of that text in Egypt can be traced via scraps of copies, like fragments of copies that were found in the Cairo Geniza. So there is a late 10th century copy in an Iraqi hand of the Rasat-le-Huana Safa that I put an image of in the book because it was found in the Cairo Geniza. So it's a wonderful kind of unsung source for people who want more Arabic sources to work on. Well, that's fantastic. There's a question about, when you were talking about the Hebrew script scribes, you talked about the Hebrew script coming at right angles to the Arabic script and the Arabic being vertical. Was that just part of the description of the picture that you showed, or was it a practice at the time? Are you able to comment on that? Sure, there's no kind of pattern that you can really discern. The Hebrew script scribes will write between the lines in any way that they possibly can, and it all depends on what they're writing. So with letters, often they're writing parallel to the Arabic lines with more ephemeral sorts of texts, like notes that will often write perpendicular, but I wouldn't go to print with that without running the statistic first. Sure. There's a question about whether there were any clues in the documents about why Ismaili theology and ideology was not spread amongst the people of Egypt because at that time, according to the question, Ismaili Dawah activity was mostly abroad. Any inferential clues perhaps from the material or you'd rather not answer that, I don't know. So I have nothing directed on that, but I will say, and this is kind of really in the realm of the circumstantial, but it might help for some context, that you really get the sense from the texts that were produced by government officials for the government, as opposed to whatever they're writing in their spare time, which could have been theology or anything you can imagine, that these were two separate realms, that Fatimid ideology was one thing and the day-to-day business of administration was another thing. And the ideology wasn't like, the first thing in any official's mind when they were collecting taxes, except to the extent that somebody like Al-Qa'diyah No'Aman, the architect of Fatimid law, had said in the 10th century, if the people you're collecting taxes from need a delay, need a kind of extension into the next year, please give it to them because ultimately, we're about mercy, we're about justice and mercy and we're not about oppression. That's as far as it goes on a level of practicality. But that's really one of the big issues in Fatimid studies today is that there are very few people, I mean, Paul Walker is one of the great exceptions, but there are very few people who study both Fatimid philosophy slash theology on the one hand and Fatimid politics and administration on the other because it's kind of hard to find those meeting points. Like I have this one official I'm working on who I know is doing both.  Like it seems like there's really no mixing between these two sides of his activity. There's a question that is particular to whether the Geniza documents tell us anything about the state of and relations between carrot and rabbinical Jews in the Fatimid empire. Did you look into that at all or? I'm so glad you asked, I wrote a whole book on that. So this is actually interesting. So my first book, which I published in 2008 on heresy and the politics of community was on exactly this question, which is carrots and rabbinites, the two main movements or schools of Judaism in this period and carrots and rabbinites were both, you know, substantial communities in Egypt. They, what we had until people looked into Geniza documents was just the polemics between them.  But in fact, Geniza documents, there had been some published in the 50s and some more in the 90s. And then I started to dig into it more that suggested that not only did they get along when they needed to or in certain contexts, but also they married each other. So we have examples of carrots and marites and rabbinites marrying each other and deciding and writing into their marriage contracts what their religious observance is gonna look like and how they're gonna, you know, kind of they basically pre-negotiate all of the significant practical differences between the way they observe Jewish law. So that, you know, experience of kind of like, let's see what happens when you throw the Geniza at this problem and realizing that the polemics are just one aspect of a much, much more complex social picture. I would say that unconsciously that's kind of what like led to this interest that I was talking to you about before of in how the Abbasis and the Fatimids were actually quite similar, right? And would borrow from each other as opposed to just polemicizing against each other. That's fantastic. Marcus, do you have any question coming in? Because I think I've asked you. Yeah, there was one that actually Dr. Arash is saying that I was thinking that if we're not mistaken, did you mention the script, you know, going from East to West? What was it? Could you elaborate on that the Arabic calligraphy at this period, you know, going from East to West? Can you just maybe have some touch upon that? Absolutely, thank you for the question. So here I'm building on another body of work by Jeffrey Khan, who is like an amazing scholar in many, many different subfields of Semitic language studies. And he did a number of studies on a kind of notable change that happened in the script that you find on Arabic, the Pairi from Egypt in the 9th century. And he calls this the Pahlavi substrate. So why does he do that? Because it turns out that there were an enormous number of bilingual administrators, Pahlavi or Persian and Arabic, who first of all, were working for the Abbasis in the Khorasan in the 8th century. And we know this because small archives have been excavated that have some documents in Pahlavi and some documents in Arabic. And if you look at the Arabic and you don't know that it's Arabic, you really don't know what it is. And you're like, is that Pahlavi? And then Jeffrey Khan comes along and is the only human on the face of the planet who can actually decipher them. So he matched that script with the change that you have in Egyptian Pairi in the 9th century. And realized that the chroniclers also talk about all of these bilingual administrators coming from Khorasan into Egypt and bringing their scribal styles with them.  So that was what got me thinking, okay, so we can see this Pahlavi substrate, right? Coming from Khorasan to Egypt in the 9th century. We see paper coming from Khorasan to Egypt in the 10th century. What else are we gonna find? So that was when I started looking at the development of Arabic calligraphy in the 10th and 11th centuries. And this was like so fascinating to me because I really wasn't expecting to go in this direction. But it turns out that the Abbasid Chancery scribes had a lot of Persians, a lot of Iranians working there. A lot of whom were Iranians and all of this is happening under the Bouyets also, which is important to remember, are very concerned with classical proportioning in script. And it actually has, it's the same circle as the Yihuan Asafah who write also a lot about geometric proportioning. This here I'm building on the work of Ana George at Oxford. And so if you kind of, we don't have a lot of physical evidence of Abbasid Chancery styles from the 10th century, but there is that one document I showed you and there's some like writing about Abbasid Chancery styles and to the extent that we can reconstruct them, the best evidence that we have of what an Abbasid document would have looked like in the 10th century is what a Fatima document looked like in the 11th century. So that's that westward movement. And it's interesting, a couple of the scraps that you showed, I really thought there was almost a panel of the letters in there. I mean, you know, just a snapshot was there and I think am I right that maybe in Balch, in a Dr. Aruzu Azad as she got this project, I mean, she is probably finding similar things but around Balch and around, you know, it's extraordinary this level. I thought also some of the, I mean, I find the Arabic script of that period that you're showing, you know, some of the Qorans, for example, was yet totally ineligible, but I thought some of the material you showed, I mean, even I as a person, I thought, I can read this, I can work it. I mean, it's very clear, very non-10th century, you know, it's extraordinary. The clarity is a big point that the people who talk about Arabic calligraphy in the 10th century talk about, they're like, you know, they're really focused on clarity but I have to warn you, it's deceptive. So I also, when I first started looking at these decrees, I was like, oh, it's so clear. And then you realize like, they're not always writing with dots and they do this thing called, that the field has come to call abusive ligatures where you connect letters that aren't supposed to be connected and it can be very challenging. And that's kind of actually the beauty of them is that they seem so clear, but they're so kind of like mysterious at the same time. And that's also what makes them totally addictive to work on as a historian. And just to say, because you mentioned Arzu Azad's project, Invisible East, which is a fantastic project to bring together many different corpora of documents from the Persianate world in the, you know, 8th, 9th, 10th, 11th century and exactly in this period, and a bit later as well, I think they go through the 13th. And some of the documents that her project is working on, I also talk about it in my book because it's kind of like the Eastern manifestation of the Abbasid Chancery script. So they're very much connected. I wondered whether I thought in your book, I ought to check to see whether there is an overlap. Absolutely. And there's, I think, a question. If the scholar, you mentioned that Oxford, I think the names that who written about Iqwan al-Saffa, here, the written about the proportion and calligraphy, could you kindly repeat the name of the scholar? This is Alain Georges. And the book is called, I think, The Rise of Arabic Calligraphy. If I'm not mistaken, I could be getting that wrong, but it's a fantastic book where he actually draws the circles and the lines so that you can see the proportioning of the script and not just the curvilinear script. He also talks about kufik script being very, very carefully proportioned. But he was the one who kind of found the link to the Iqwan al-Saffa, that they talked about classical proportioning as really a matter of kind of philosophy. But, and they talk about it with music, they talk about it with geometry and engineering, and they're very concerned with these kinds of issues of proportioning, and it's the same people who are involved with that circle of the Iqwan al-Saffa, in some cases, the same exact people are writing, either working for the chance or writing treatises on how to write beautifully in Arabic. I think maybe some of that is also covered by Professor Stephen Sperl's book on Arabic script on what was it, the divine script. I think he has that historical bit about how, you know, it was actually a science and the art of writing, yeah. But the idea of proportionality in calligraphy and how it's reflected even in the design and the architecture and the prints is very interesting. I think we're coming almost to the end. I think so, yes. We're coming to the end of such a brilliant time, Melina. Thank you so much. We have so many people saying amazing talk, and we just remind the audience where they can get the book. Hopefully they will buy it, and we look forward to hosting you again. Absolutely. Thank you so much. Thank you for the excellent questions, and thanks for the opportunity to talk to you. I appreciate it. Thank you, and Aki will share the recording with you just in case you want to look at it before we share it with the audience. But thanks a lot. Have a nice day. Thank you so much. And see you soon, hopefully. You too. Stay safe. Thank you so much.  Thank you. Bye-bye.


What's up, everyone? It's Tony's over here. It's been a while and today I just want to make a video on You know the styles we've been trading today. I mean it is a really difficult day You know, this is time of the day that Wipes out, you know Month and like weeks months or even the year P&L if you don't have a discipline and it is a really tough day and so that's why I Kind of you know, I want to address a few Things that I think it could be helpful for you guys and also For those that haven't experienced this type of event before so, you know today's basically the topic is going to be about How to kind of trade the black swan event or like the black swan stocks and Yeah, what else? DWAC Digital, you know word Yeah, yeah, probably you guys know the news, you know trauma involved in this one and you know, it's just suddenly when it's like nuts like basically and You may do that stock great again Today and it it is really tough day for a lot of us Alex as well, I think a lot of people You know lost, you know in the room as well and Yeah, so I hope you know I just want to kind of do the video today. So the idea is fresh. So, you know, I don't forget about it and and I just think that you know a lot of lessons can be learned from Today's video so So as this morning As it was in the pre-market, I Mean, we saw it tanking, right? I mean This is like the top is set pretty much Let me zoom in to this one top is set pretty much 20 line you know and it just keep going down down down further, right and It was pretty early. So I don't think anyone could be in this type of move Like I like I don't think anyone shorted that But for me, I shorted some here at you know, 1250 1237 actually Pause in the room and I got out at 12, right? It was like for 30 cent and shit dumped another You know almost like two bucks here from this $1.50 and And yeah, as a day goes by I mean, you know When you see something like this, of course, it is a broken stocks, right?  I mean, this is one of those lot of liars that it happens. Maybe Once in I don't know like a year.  I mean, it's it's not like it's like it's not a hundred percent, right? I mean Anything can happen. That's why in trading, you know, it's like that and You know risk management that that's everything that you can do, you know Long or short doesn't matter if you trade on the fly on this one You just want to get in and think about it later.  I think it was here like margin calls a lot of people here Yeah, I mean, but this is what it is and Like I said, black black swan stocks see it breaks above this Like don't touch it if you knew okay, if you don't know what to do just watch and and you know gain experience gains The the the screen time for next time, right? And once you get better at this, you know Like you can scobble around, you know, the the good psychological kind of line Like I said, you know, 50 100 150, you know, if it gets Extended enough To those lines, I don't want to be shorting into this grinding high and grinding high I want for the stock to kind of extend enough and when it gets to 50 back in my mind, okay It was psychological line was you know, why I didn't short it 30 why I didn't short it 40 Why didn't you short it 45? All right, but I chose the 50 line to get in short and It breaks that 50 next one for me would be 100 I don't want to be messing around with 60 70 70 565 something like that But that was like, you know, it's it's not really That matter because it was a small size and there's no way that you can size up on something like this Okay, so if you miss that don't worry about it I think the most important thing that you are safe When shit like this happens and that's the most important thing, right? That's why you are in my seat We will tell you to protect your account to be careful Especially if you knew Just you know, watch the stocks how it behaves so that you can understand it for next time when you see this time It stopped. Okay, don't worry about making money on those worry about that, you know Were you able to To stay safe during this, you know period or like, you know, like doing like today, right? making zero is still better than You know down 500 bucks or like $1,000 on this and And yeah guys, so I hope this is like a good lessons for you guys on, you know, this type of Event I hope I think you know on this one I would wait until the first red day, of course, right? Let's see if it, you know runs much higher, but we all know that is, you know, 10 to 50 guys. Come on with that much volume When it turns it's gonna be bloodbath, right? So as a short seller we wait for the back sign and then we attack Okay, that's the safest way how to do it You don't need to anticipate what I do today.  That's fine as long as you have pretty fine rest Oh good to me. What like I said here, you know, if you knew ignore it and Just wait until it turns right That's CEI AMC GME pretty much the same thing


Hello everyone. Thank you all for coming here this morning. My name is João Paulo. I work as a software engineer in the Bluetooth team at INDT. I've been working with improving the support for Bluetooth flow energy on Linux and also with IVI related Bluetooth profiles. So today I'm going to talk to you about the support of Bluetooth flow energy and Bluetooth smart device on Linux. So that's the agenda I have. First I'll talk a little bit about the technology itself, like how it does discovery, connection, how the protocols and profiles works, and then I'll tell you what's the status of all of that on Linux. But before getting into Bluetooth flow energy, let's just go a little bit back in the past and remember what is Bluetooth? So Bluetooth was a technology which was designed to substitute cables when you're connecting peripherals to your computer. So it was designed with short distances in mind. And the idea was to provide a high level of security, like the same level you would get on a cable, so you're not expecting people in the next room to be able to wear tap your connection. It was created back in 1994, so almost 20 years now, by a telecom company called Ericsson. And later in 2010 we had the version 4.0 of the Bluetooth specification which defined Bluetooth flow energy. So it was aimed at low power consumption, especially on the peripheral side. So if you come here to learn how to save power on your laptop, I'm sorry. And so the idea is to enable devices that are powered with coin cell batteries, which is usually the battery used on wristwatches, that small round battery. And to have these devices to work for about two years with one single battery. So for that they improved the connection establishment. So the radius between the two peers synchronizes much faster. They have less channels to scan. So you could have a physical connection between these two devices established in about three milliseconds, which is really fast. It's still focused on short range, so that haven't changed. And one economic advantage of that is that they are reusing the same radio that is used by classical Bluetooth. So the cost to have a classical Bluetooth hardware upgraded to a Bluetooth low energy is very, very low. Just some additional structures have to be added, but the radio itself is the same. One drawback of that approach is that classical Bluetooth operations and Bluetooth low energy operations cannot be done in parallel. So you have to multiplex them somehow. And the market they had in mind when creating this Bluetooth low energy besides the market for classical Bluetooth devices, consumer electronics, like you have Bluetooth low energy input devices and these kind of things, mobile phones as well. But they mainly wanted to add these three new markets, the fitness and wellness where you would have like hard heat meters, Bluetooth enabled, wristwatches, pedometers, all this fancy sports device. Medical device as well, like blood pressure monitors, oximeters, glucose monitors, body thermometers, and sensors. So general sensors for like room temperature, gas sensors, proximity sensors, motion sensors, all this kind of stuff, talking to each other wirelessly. They also came up with new branding to refer to Bluetooth low energy devices, which made people a little bit confused in the beginning. So they came up with this Bluetooth smart devices concept, which is basically devices that use Bluetooth low energy to communicate. So it's mostly on the peripheral side. And the Bluetooth smart ready device, it's a classical Bluetooth which can also talk to a Bluetooth smart device. So it's basically what we call dual modes. They have a dual mode radio, which speaks classical Bluetooth and also Bluetooth low energy. That's mostly the computers and mobile phones. So to be able to save power, they also change it quite a bit how the devices find each other and connect to each other. There is a profile in Bluetooth called the generic access profile, which basically defines the procedures for devices to find each other, connect to each other, and also how they use different security levels. So that's the profile statement over there. So the gap profile defines two different types of communication for Bluetooth low energy devices. One is connection oriented, where you have these two roles, the central and the peripheral. They find each other, then they establish a connection before starting to communicate. And also there is a connection less communication between the roles broadcaster and observer. The arrow there is a little bit inaccurate because this communication is unicast, so it's basically communication from the broadcaster to the observer. And they communicate through the discovery process. So when you are using the central and peripheral roles to discover each other, the central device starts scanning. This is scanning, as I said before, it's low energy only, because the radio is shared, so it's concurrent with classical Bluetooth operations. So the BRNDR inquire there is the classical Bluetooth discovery procedure. And it has a configurable window and interval. So the window is basically the amount of time that the radio is actively scanning. And the interval, it's the amount of time that passes between one scanning window starts and the next scanning window starts. So with these two parameters you can configure your dirty cycle, which will influence how fast you can find your device or how likely it is to find your peer device, and also how much power will you expand using that. So usually the profiles have recommendations on how to configure that for different phases of the profile, like after a link is lost or when first looking for a new device. And on the other side, the peripheral simply indicates its presence. So to indicate its presence, it broadcasts small data packets, which are called advertising reports. So the advertising reports are used to indicate the peripheral presence and also to indicate what's the state of that peripheral. So what can the central do with it? There are four different states that it can be. The most common one is the Connectable Undirected Advertising Report. And when the peripherist advertises that, it means that it shall accept a connection request coming from a central device, more of that from any central device. Then we have the Connectable Directed Advertising Report in which the peripheral shall accept a connection request but coming from a non-peer device. So it's directed at a specific central device. Then we have the Scannable Undirected in which the peripheral shall not accept a connection, but it shall answer scan requests coming from any central device. So a scan request is basically package the central sense to gather more information about the peripheral device. So it shall answer this request with scan responses. And then we have the Non-Connectable Undirected in which the peripheral shall not accept a connection and nor answer to scan requests. And then when the devices find each other, the central starts a connection establishment procedure. The connection is always started by the central. It's not possible to have a connection request by the peripheral. So usually if the peripheral is interested in a connection, what it does is it starts advertising and wait for the central to try to connect to it. And there are three different connection establishment procedures defined for Bluetooth flow energy. The most simple ones, the direct connection establishment procedure in which the central simply sends a connection request and the peripheral answers that with a connection response and the connection establishes it. And the general connection establishment procedure and the auto connection establishment procedure you actually configure your central to be scanning and when it sees a peripheral that is interested in it sends a connection request. The difference between these two procedures is that in the general one this configuration is made on the host. So the host put the radio to scan, receives all the device found events and filter to know if that's the device is interested in or not and then sends a connection request. For the auto connection establishment procedure we have some support in the hardware. It's called the white list. So you configure the harder white list with the peripheral addresses you're interested in and then this filtering is done in the hardware. So your host is just awakened when the connection is actually established. So the hardware is scanning by itself when it sees the peripheral you're interested in it tries to connect if the connection is established successfully then your host is notified. So you can save quite some power over that. Also the security provided by this communication model. We have a secure manager protocol which was designed specifically for Bluetooth flow energy. So it provides payload encryption and authentication. Most of the calculations involved in the cryptography of that are done in the central role which is the one that usually has more processing power and more battery power as well. And the encryption engine used is AES 128. So it's easy to add hardware support for the encryption involved in that. So it's something that could save also more processing power and battery power. And it provides three methods for authenticating your peer. When it just works it's basically not authenticating your peer. So with this method you are like that can happen many in the middle attacks. But if you use the pass key entry or the out of band one it provides many in the middle protection. The pass key entry is basically you enter the same pass key on both devices and out of band is when you use another transport to do the authentication. So it could be over NFC so you just bring the two devices together and establish an NFC communication to exchange keys and do the security manager protocol. Or you could connect a cable between these two devices, something like that. And then we have the broadcaster and observer communication which as I said it's connection less. It's a unicast so the data is transferred from the broadcaster to the observer. It uses very small data packets so the whole advertising report if I recall correctly is 39 bytes long but you have the headers and all of that so you get about 27 bytes in the best case per report that you can use. So basically it can be used for some sensors like you could have a room temperature sensor or you could have advertisements like if you go to a shopping mall then there are some stores advertising discounts or this kind of things or transport information in a transport hub so which is the next car arriving or maybe artwork information you go and I'm using. These kind of small informations that are usually always the same so you just want to let people know what's happening in that place. There are no profiles defined by the Bluetooth SIG that use that information yet, that communication model yet. But there is room for you to have a manufacturer specific data in there so basically all the communications that use it now uses the manufacturer specific type of advertising report. So the protocols and profiles involved in Bluetooth flow energy. So basically this is the protocol stack. The great part in the bottom there is inside the hardware. Then the hardware provides a host controller interface for the host and the L2CAP protocol, it's the transport protocol used by Bluetooth. It's the same one as used by Classical Bluetooth. You can think of it as the TCP of Bluetooth. And then all the upper part in orange I think there. It's profiles and protocols that were defined specific for Bluetooth flow energy. So we have the attribute protocol on top of that the generic attribute profile and then the use specific use cases profiles are defined on top of the generic attribute profile. So I'll talk about each of these boxes now. So the attribute protocol, it's basically a protocol to allow discovery and read and write of attributes on a peer device. It works on a client server model. So the server have a bunch of attributes that the client can read, write and also the client can be notified about changes of the value of one attribute on the server side. Attributes are basically a pair of a handle, I'm sorry, it has a handle which is like an address and then it's a pair of a type and a value. So it's like, you can think of it as a, yeah, like a pair of two values. So and it works in this way because it was designed for small data transfers. So you can also save power when transferring data. You don't have to have your radio turned for a long time to be able to transfer data. So then on top of that we have the generic attribute profile which tries to organize this bunch of attributes a little bit. So the attributes are grouped into something called characteristics. A characteristic is basically it has a declaration attribute which says what is the UID of that characteristic and what is the access mode of that characteristic. So if you can read or read and write, it has a value attribute which has the value associated with the characteristic and it has, so those two are mandatory and it can also have some descriptors for configuration, for data format, for example, if you have a room temperature sensor and you, a descriptor would be easy to inform what's the unit of the temperature being measured if it's in Celsius or Fahrenheit. And the configuration is easy to be able to enable notifications of changes on that characteristic. So the client can use this descriptor to ask, okay so when the temperature changes please send me a notification. And then these characteristics are also grouped in a bigger group called services. So basically a gut service is a set of characteristics and then a characteristic is a set of attributes. So I have some little example to make it, try to make it a little bit clearer. So here we have a hypothetical gut server with three attributes there, handle 23, 24 and 25. So for the first handle the type it's 2800 which is a primary service declaration and then the value says what's that service that being declared there which here is link loss service which is part of the proximity profile. Then we have the first characteristic of that service on handle 24. So the type is 2803 that means it's a new characteristic being declared. So that's the declaration attribute I talked about before. And as I said it has the properties which is the access mode of the characteristic. So it's zero way that means you can read and you can write and get a response of your right request. And then it comes watch handle the value attribute for that characteristic is located. As you can see it's 0025. Then last we have the UID of that characteristic. So it's an alert level characteristic which is part of the specification of the link loss service. And finally on the handle 25 we have the UID of the alert level characteristic again. So it's 2806 and then the value of 2 which for those characteristics means a high alert level. Okay so one of the profiles that uses the link loss service is the proximity profile. So basically in this profile you have two rows a reporter and a monitor. And when they distance from each other the an alert is emitted on the reporter. So this alert level is configurable using that characteristic that I showed you before. And there are two different mechanisms to tell when the devices are far away from each other. One is link loss which is that service that I showed you. Basically the alert is emitted when the actual physical link between the two devices is lost. And the other one is path loss. In this with this service the reporter device also indicates what is its transmitting power. So the monitor monitors the RSSI level which is like the power that he is getting from on each packet. So then it can like infuse the distance between the two devices. And there's a configurable threshold where you can say oh when it goes over this distance even if the link is not lost let me know. So then the alert is emitted. Another profile defined by the Bluetooth 6 defined me profile. It's similar to the proximity profile but instead of relying on a distance being over a certain threshold it waits for some kind of user input. So you have the locator where you would have a button or something like this to tell okay let me know where the target is. So the locator writes on the alert level characteristic in the target and the target emits an alert level. And also the alert level can be configurable. We have the heart hate profile as well which is used for that heart hate belts or heart hate watches. So there are two roles a sensor and a collector. The sensor reads heart hate measurements and sends it over to the collectors, to the collector. This one example of characteristic notification. So basically the collector configures the sensor to enable notifications of changes on that characteristic. It also uses descriptors on the characteristic to specify the format of the heart hate value being sent over. There are some different formats that can be used. Also it indicates if the value contains a field called energy expended and the presence of the RR interval as well. So it's field specific to heart hate measurements. There is also another characteristic to provide the where in the body that sensor is used. And there is another characteristic to reset the energy expended field. So the collector would write on that characteristic to reset that. The health thermometer profile, it's similar to the heart hate profile. Basically there is a body thermometer that sends temperature measurements at periodic times. The head over gut profile, they basically encapsulated HID protocol inside heart protocol. So you have a characteristic where you can get notified about HID reports. So every time like a keyboard wants to send a HID report, it actually changes the value of the report characteristic. And since the host has configured notifications for that, it's notified of that value change. It also has a characteristic to store the HID descriptor so you can get that to configure your new input device. One advantage of this profile is because since we have much faster connection establishments with Bluetooth low energy, you don't have that feeling of, oh, my mouse is not working. Okay, now it's working. That usually happens with classical Bluetooth devices. If any of you had one, you know what I'm talking about. And yeah, we wrote the support for this profile at INDT. So we basically created a new kernel interface to be able to create HID drivers from user space. It's similar to UInput. It's called UHID. Maybe it can be used for other things as well. Another profile is the time profile which provides client server synchronization of time. So you have a time server and then your client talks to that server to synchronize the local time, the time zone information and the DST information. So if you are currently on DST and what's the offset, so there are some citizen and Casio watches that already have that. It's really cool.  I don't know. I found it really cool. And what's the support of that on Linux currently? So the kernel support was enabled by default in Linux 3.5. If you're still running something older than that, probably from 3.3 something, there are module parameters to enable experimental support for Bluetooth energy, but I would not recommend you to do that. It would be much better if you can get the newer kernel. So for discovery procedures, we support both LE-only scan that can be triggered through the user space and also something that the specification calls interlimited scan, where you would do 5.12 seconds of low-energy scanning plus 5.12 seconds of BR&DR inquire. So this way you could mimic that you're doing both classical Bluetooth and low-energy Bluetooth operations in parallel, so you can find both kinds of devices. It works pretty well. On the connection procedures, we have support for the direct connection establishment procedure in the kernel. So basically you just create a new Bluetooth-learned socket and it shows a connection called to them, to it, and then it will send a connection request over to the address you passed. And we have the general connection establishment procedure implemented in user space inside Bluetooth D. So to be able to use that, you have to use Bluetooth D for your low-energy connections. Basically we keep a list of the device we are interested into, but the radio into scanning mode, filter that in user space, and so on. The auto-connection establishment procedure is not supported yet. We have plans to do so, but it's not done yet. Also, we added support for the security manager protocol inside the kernel, both for the just works and the pass key entry authentication methods. We don't have support for out-of-band authentication yet. If I'm not mistaken, there is some support for out-of-band over classical Bluetooth. I remember there were some patches, but I'm not completely sure if they made upstream or not, but I think so. So it shouldn't be much work to add out-of-band to Bluetooth low-energy, but as far as I know, nobody is working on that right now, if you're looking for something to do. On the profile support, we have support for all the profiles I said before, and also the cycling speed and cadence, which is basically the devices that you attach to a bicycle and that's cool, and we'll tell you the speed you're going by measuring wheel revolutions and these kind of things. Currently, we are working on a generic attribute profile API. We used it to have one, but when we changed it to BlueZ5, Marcel wasn't really happy about how that API worked, so we decided to just remove it completely and start over. So that's one thing we are doing at INDT. Actually, we have wrote the code for it already, and we presented it at the last wireless summit in New Orleans about a month ago. So now we are fixing some changes we have requested during the summit, and hopefully it will be upstream a month or something like this. Let's see how things go, and we are also working on implementing the generic connection establishment procedure inside the kernel. It's also like most of the code are written, but it's going under peer review right now on the mailing list, and when we finish that, we want to add support for using the harder white list for the automatic connection establishment procedure. So yeah, that's what I had for you today. So if you have any questions or anything? Yes? Alright, so the question, what's the status of Bluetooth Flow Energy in BlueZ4 and in BlueZ5, right? Okay, so for Bluetooth Flow Energy, basically we had support for Bluetooth Flow Energy since BlueZ4.99 I think. So if you use either 4.99, 4.100 or 4.101, you have the initial support we wrote, but then we continue to evolve it through the new versions of Bluetooth. So there is nothing specific in the Bluetooth Flow Energy area new because of the BlueZ5 change, but just the general API of BlueZ has changed basically. So for low energy, besides the code being more mature and all of that, that you would get if we didn't have changed the major version anyway. Did I answer your question? Okay. Okay, so if you want, feel free to come to talk to me afterwards or any day in the conference. I'll be here until Saturday, and you can also send me an email or find me on IRC. So that's it. Thank you very much.