Non-Euclidean geometry that are both perpendicular to a third line: Euclidean geometry, named after the Greek mathematician Euclid, includes some of the oldest known mathematics, and geometries that deviated from this were not widely accepted as legitimate until the 19th century. The debate that eventually led to the discovery of the non-Euclidean geometries began almost as soon as Euclid's work "Elements" was written. In the "Elements", Euclid began with a limited number of assumptions (23 definitions, five common notions, and five postulates) and sought to prove all the other results (propositions) in the work. The most notorious of the postulates is often
Transmission of the Greek Classics referred as translating into Syriac the chief medical authorities as well as parts of Aristotle's "Organon". After studying at Baghdad under Yahya he visited Alexandria and returned, not only with the training given at what was then the first medical school, but with a good knowledge of Greek which he employed in making translations in Syriac and Arabic. Later the Caliph al-Mamun also sent emissaries to the Byzantines to gather Greek manuscripts for his new university, making it a center for Greek translation work in the Arab world. At first only practical works, such as those on medicine and technology