This essay focuses on the role of optical and anatomical representations in the works and thought of Leonardo da Vinci. The author touches upon a series of controversial questions concerning the sources and character of ancient and medieval knowledge that influenced the artist’s worldview. By analyzing anatomical drawings, diagrams, and paintings, the paper compares the laws of universal mechanics with the logic of Leonardo’s compositional thought. As a graphic example, the author demonstrates that the logic of figures’ rotation around the composition’s axis in «The Virgin and Child with St. Anne» (1500-1507, Paris, Louvre) recreates the scheme of movement of the heavenly bodies around the earth, in accordance with Ptolemaic epicycles.