 This reference to the name "Darius" was used in the 19th century commentaries of Keil and Delitzsch and Lange to assert that "Darius the Mede" in the Book of Daniel was attested in an ancient source.Harpocration was a lexicographer who wrote in the latter half of the 2nd century AD.He was associated with the great library at Alexandria, and had access to many ancient resources that were lost when the library was destroyed.