THE LIBERTINE'S NATURE is a book about the infamous Marquis de Sade. His works teem with uninhibited libertines who ruthlessly take advantage of others. The will to excess is also in evidence when the libertines raise the torch of philosophy as part of their debauchery. They talk a lot, but how do they think?This is a book about Sade's philosophical thoughts.In the context of the history of ideas, Sade is interpreted as a philosopher along the lines of other writers of the Enlightenment. His conception of nature claims special attention in this respect. His reflections concerning comparative anthropology and the aesthetics of the sublime are also emphasized and discussed in connection with Rousseau, Kant, and Nietszche, among others.In the perspective of what is termed Social Analytics and with Sade as the point of departure, elements of a theory of pleasure are constructed. With lust as the fundamental category the aim is to complete a revaluation of the priority traditionally given to 'the other' in moral philosophy. The goal is to formulate a different ethics beyond the opposition between desire and decency.