 Theodosius' primary function in this, and other, works is to gather together existing information into one place.In the first book of Sphaerics, he carefully explains that a sphere is a shape whose surface is an equal distance, in any spot, from a central point, and then goes on to examine the geometry of spheres, extensively.The work's primary importance was in the restoration of Euclidean geometry to European knowledge, as this, and much other technology and philosophy, had been lost to Christendom, but preserved in Arabic translations during the Islamic Golden Age, then brought back to Europe during the Crusades and translated back into Latin.