On the one hand, we tried to make the book as biographical as possible, without delving into the scientific jungle. On the other hand, it is difficult to imagine the biography of a scientist without describing the development of his ideas. This means that it is impossible to do without presenting the ideas themselves. In some cases, where it seemed convenient, we tried to intertwine biographical information with scientific information, in others - to separate them, nevertheless trying to pay attention to the processes of formation of the scientist’s views. The exceptions are Pythagoras and Aristotle. Not much reliable biographical information has been preserved about them, especially about Pythagoras, so our story includes an analysis of information sources and a presentation of the views of various specialists. Perhaps because of this the text became a little drier, but we went for it for the sake of authenticity. However, we still hope that the book as a whole will not only arouse your interest (it already exists if you have started reading), but also give you pleasure.