Many classical authors and theories occur in Kant’s work. In this first complete treatment of the topic, the author shows that, contrary to the opinion held by scholars for many years, it is not so much Plato and Aristotle as Hellenistic philosophy which plays the decisive role in Kant’s thinking. The three Critiques are used to develop the consistencies and breaks in Kant’s understanding of the Ancients and to illuminate their consequences for the interpretation of his work.