Euclid of Alexandria is the author of one of the most popular non-fiction works in history. His main work, “Principia,” was republished thousands of times; over the centuries, entire generations of scientists learned the basics of mathematics and geometry from it. This work consists of 13 books and contains the most important geometric and arithmetic theories of Ancient Greece. No less important than the content is the form in which Euclid presented scientific knowledge: from axioms and definitions, he derived 465 theorems, building an impeccable logical structure that remained indestructible until the beginning of the 19th century, when non-Euclidean geometry was created.