Foundations of geometry different sets of axioms for Euclidean geometry, any of these can replace the Euclidean parallel postulate. The following partial list indicates some of these theorems that are of historical interest. Absolute geometry is a geometry based on an axiom system consisting of all the axioms giving Euclidean geometry except for the parallel postulate or any of its alternatives. The term was introduced by János Bolyai in 1832. It is sometimes referred to as neutral geometry, as it is neutral with respect to the parallel postulate. In Euclid's "Elements", the first 28 propositions and Proposition I.31 avoid using the parallel postulate,
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