Euclid's Elements is a mathematical and geometric treatise consisting of 13 books attributed to the ancient Greek mathematician Euclid in Alexandria, Ptolemaic Egypt circa 300 BC. It is a collection of definitions, postulates (axioms), propositions (theorems and constructions), and mathematical proofs of the propositions. The books cover Euclidean geometry and the ancient Greek version of elementary number theory. The work also includes an algebraic system that has become known as geometric algebra, which is powerful enough to solve many algebraic problems, including the problem of finding the square root of a number. Elements is the second-oldest extant Greek mathematical treatise after Autolycus' On the Moving Sphere, and it is the oldest extant axiomatic deductive treatment of mathematics. It has proven instrumental in the development of logic and modern science. According to Proclus, the term "element" was used to describe a theorem that is all-pervading and helps furnishing proofs of many other theorems. The word 'element' in the Greek language is the same as 'letter'. This suggests that theorems in the Elements should be seen as standing in the same relation to geometry as letters to language. Later commentators give a slightly different meaning to the term element, emphasizing how the propositions have progressed in small steps, and continued to build on previous propositions in a well-defined order.

"The book includes introductions, terminology and biographical notes, bibliography, and an index and glossary" --from book jacket.

First published in 1926, this book contains the final volume of a three-volume English translation of the thirteen books of Euclid's Elements.

Euclid's Elements is the most famous mathematical work of classical antiquity, and has had a profound influence on the development of modern Mathematics and Physics. This volume contains the definitive Ancient Greek text of J.L. Heiberg (1883), together with an English translation. For ease of use, the Greek text and the corresponding English text are on facing pages. Moreover, the figures are drawn with both Greek and English symbols. Finally, a helpful Greek/English lexicon explaining Ancient Greek mathematical jargon is appended. Volume II contains Books 5-9, and covers the fundamentals of proportion, similar figures, and number theory.