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.
Greek Orthodox Patriarchate of Alexandria and all Africa Greek Orthodox Patriarchate of Alexandria and all Africa The Greek Orthodox Patriarchate of Alexandria and all Africa (Greek: , "Patriarcheîon Alexandreías kaì pásēs Aphrikês") is an autocephalous Byzantine Rite jurisdiction of the Eastern Orthodox Church, having the African continent as its canonical territory. It is commonly called the "Greek" or "Eastern" Orthodox Patriarchate of Alexandria to distinguish it from the "Coptic" or "Oriental" Orthodox Patriarchate of Alexandria. Members of the Greek Orthodox Patriarchate were once known as Melkites, because they remained in communion with the Ecumenical Patriarchate of Constantinople after the schism that followed the Council of Chalcedon in 451.