Theon (Greek: Θέων; ca. 335 – ca. 405) was a Greek scholar and mathematician who lived in Alexandria, Egypt. He edited and arranged Euclid's Elements and Ptolemy's Handy Tables, as well as writing various commentaries.
Theon was the father of Hypatia who also won fame as a mathematician.
The original library at Alexandria in Egypt was one of the wonders of the ancient world. Founded by Alexander the Great in the fourth century BC,built and enlarged by Ptolemy I,Alexander's successor.
The city's library comprised perhaps as many as 700,000 manuscripts - the whole corpus of knowledge accumulated by ancient philosophers,scientists and poets.And it was all contained in a building thought by the ancients to have been of surpassing beauty,not a trace of which survives .