Euclid's Elements Euclid's Elements The Elements ( "Stoicheia") is a mathematical treatise consisting of 13 books attributed to the ancient Greek mathematician Euclid in Alexandria, Ptolemaic Egypt c. 300 BC. It is a collection of definitions, postulates, propositions (theorems and constructions), and mathematical proofs of the propositions. The books cover plane and solid Euclidean geometry, elementary number theory, and incommensurable lines. "Elements" is the oldest extant large-scale deductive treatment of mathematics. It has proven instrumental in the development of logic and modern science, and its logical rigor was not surpassed until the 19th century. Euclid's "Elements" has been referred to as the
The Crown of Ptolemy The Crown of Ptolemy The Crown of Ptolemy is the third and last book in the "Percy Jackson and the Olympians" and "The Kane Chronicles" crossover series. It was released in the back of the paperback version of "The House of Hades" on March 31, 2015, and later as an ebook and audiobook. The ebook edition was released May 12, 2015. On January 15, 2015, Rick Riordan announced a third crossover story titled "The Crown of Ptolemy" on his Twitter account. His announcement included the fact that the short story would be first published in the paperback version of "The