# Euclid’s Elements

Euclid’s Elements is a collection of thirteen books on mathematics and geometry written by the ancient Greek mathematician Euclid, dated around 300 BCE. Euclid, the “Father of Geometry,” lived and worked in Alexandria, Egypt, during the reign of Ptolemy I. The Elements has been described as the most influential textbook ever written. Euclid’ Elements was especially significant in the development of science during the Renaissance and Enlightenment. Copernicus, Kepler, Galileo, and Isaac Newton all used the text in the development of their own work.

Through a series of axioms and theorems, Euclid defined both classic geometry and Greek number theory, forming the basis of both logic and much of modern science. While much of the book is based on the work of earlier Greek mathematicians, including Pythagoras and Hippocrates of Chois, Euclid updated or replaced many of their proofs with better ones of his own workings.

Of the thirteen books, the first four are concerned with plane geometry, including the Pythagorean theorem, square roots, and polygons. Books five through ten introduce ratios and proportions, including basic number theory such as prime numbers and Euclid’s algorithm for discovering the greatest common divisor. The final three books cover spatial geometry, including the volumes of cones, pyramids, and cylinders, as well as the five Platonic solids (tetrahedron, cube, octahedron, dodecahedron, and Icosahedron) that are inscribed in a sphere.