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.
Ptolemy II Philadelphus Ptolemy II Philadelphus Ptolemy II Philadelphus (, "Ptolemaîos Philádelphos" "Ptolemy, lover of his sister"; 308/9–246 BCE) was the king of Ptolemaic Egypt from 283 to 246 BCE. He was the son of Ptolemy I Soter, the Macedonian Greek general of Alexander the Great who founded the Ptolemaic Kingdom after the death of Alexander, and queen Berenice I, originally from Macedon in northern Greece. During Ptolemy II's reign, the material and literary splendour of the Alexandrian court was at its height. He promoted the Museum and Library of Alexandria. He erected a commemorative stele, the Great Mendes Stela. He also led