The important dialogue that Kant entertained with ancient materialism has only rarely been acknowledged and studied. The relation between Kant's thought and the theories of Epicurus and Lucretius touches on central philosophical problems. In the first part, an overview of ancient materialism is given, focusing its attention on those theories which have had a strong influence on Kant. Based on the results, the authors trace the presence of ancient materialism in Kant's works. Kant's debt to ancient materialism can be reconstructed in different fields of philosophy. The authors examine the presence of the philosophy of Epicurus and Lucretius in Kant's concepts of sensation and perception, in his theory of pleasure and pain, in his thought about God, in his pre-Darwinian idea of evolution and natural selection in biology, and in the elaboration of the concept of sublime. The purpose of the present volume is to fill a substantial gap in Kantian scholarship by examining the philosopher's debt to ancient materialism.