Two courses of lectures on Leibniz were given by Gilles Deleuze at the University of Paris-VIII (Vienna) in 1980 and 1986-1987 and were the last lecture courses in the life of the philosopher. Under the cover of the book - printouts of tape recordings that preserved the living intonation and emotional structure of Deleuze's speech . In contrast to the book he wrote later, “Folding: Leibniz and Baroque”, the lectures unfold a much more voluminous picture of the work of the German thinker. Particular attention is paid to the analysis of the relationship of Leibniz's mathematical discoveries with his philosophy, the parallels between Leibniz, Spinoza, Descartes, Kant and Whitehead, as well as the main concepts of Leibniz metaphysics. Leibniz’s philosophy becomes not only the key to understanding the Baroque era, but also the most important tool for constructing a modern picture of the world.