The book is dedicated to one of the most interesting and at the same time controversial problems of early Greek culture - the Pythagorean question. Based on an analysis of ancient sources, the author introduces the reader to the life and work of Pythagoras, the political practice of Pythagorean society, and the religious and ethical teaching of the Pythagoreans. A special place in the book is given to the scientific activities of the early Pythagoreans and their contribution to the development of ancient Greek mathematics, physics, astronomy and biology, as well as the mutual influence of science and philosophy in this school. The book is intended for historians, philosophers, scientists, as well as a wide range of readers interested in ancient philosophy and science. Table of contents: Introduction 3I. Biography of Pythagoras: sources, facts, legends 11Sources (p. 12). Life on Samos (p. 16). Travel (p. 18). Magna Graecia (p. 24).II. Pythagorean Community 30Secrecy (p. 37). Did the Pythagoreans attribute their scientific achievements to Pythagoras? (p. 40). The oral character of early Pythagoreanism (p. 42). What community did Pythagoras found? (p. 43). Pythagorean acousmas. “Mathematicians” and “acousmaticians” (p. 48). III. Mathematics 56Early Greek mathematics and the East (p. 56). Deductive proof (p. 61). Mathematics of Pythagoras (p. 67). Hippasus (p. 81). Pythagorean mathematics of the first half of the 5th century. BC e. (p. 84). “Geometric algebra” and Babylon (p. 86).IV. Music, harmonica, acoustics 91V. Astronomy 108Greek astronomy and Babylon (p. 108). Hypotheses and observations (p. 113). The doctrine of heavenly harmony (p. 120).VI. Medicine and life sciences 130Crotonian medicine and Pythagoreanism (p. 134). Medical theory and practice of the Pythagoreans (p. 137). Botany (p. 144). Anatomy and physiology (p. 149). Pythagoreans and the Hippocratic Corpus (p. 153).VII. Philosophical views of the Pythagoreans 159Is everything a number? (p. 159). Aristotle and the Pythagoreans (p. 165). Pythagorean philosophy (p. 174).Afterword 182List of abbreviations 188