  The late fifth and fourth centuries B.C.E. saw many important developments in Greek mathematics, including the organization of basic treatises or elements and developments in conceptions of proof, number theory, proportion theory, sophisticated uses of constructions (including spherical spirals and conic sections), and the application of geometry and arithmetic in the formation of other sciences, especially astronomy, mechanics, optics, and harmonics. The authors of such treatises also began the process of creating effective methods of conceiving and presenting technical work, including the use of letters to identify parts of diagrams, the use of abstract quantities marked by letters in proofs instead of actual numerical values, and the use of proofs. We cannot know whether Aristotle influenced the authors of technical treatises or merely reflects current trends.