Foundations of geometry possible exception of the parallel postulate) that any theorem proved from them was deemed true in an absolute, often metaphysical, sense. Today, however, many other geometries which are not Euclidean are known, the first ones having been discovered in the early 19th century. Euclid's "Elements" is a mathematical and geometric treatise consisting of 13 books written by the ancient Greek mathematician Euclid in Alexandria c. 300 BC. It is a collection of definitions, postulates (axioms), propositions (theorems and constructions), and mathematical proofs of the propositions. The thirteen books cover Euclidean geometry and the ancient Greek version of elementary number theory.
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