Initially, I conceived a book about the astronomical system of Claudius Ptolemy, but such a book already exists, it is called “Almagest”, and Ptolemy wrote it himself. The only problem is that the Almagest is very difficult to read, so few people are familiar with it. I wanted to write something much more understandable, but not simplified, so that the full depth of ancient astronomical thought could be preserved. It turned out that this is a very difficult task. The fact is that the only way to present the Ptolemaic system in an accessible form is to explain why, in fact, it was exactly the way it was. This required delving into Greek physics and geometry, and then, as a consequence, into ancient Greek philosophy, history, economics and politics. As a result, the work, which was small according to the original idea, turned into a grandiose canvas of the ancient picture of the world - incredibly beautiful, elegant, attractive and almost completely, in almost everything, wrong. The result is a book not about astronomy, but about why it is so difficult to invent science.