In his Critique of Practical Reason (1788), Kant takes onto himself the task of working on the problem of ethics in order to present a statement capable to base and guide human action. The categorical imperative comes to incarnate that which is the heart of an ethics called by Kant the ethics of duty, based on reason and on an allegedly pure will, disentailed of all the so called pathological inclinations, in which the individual would find pleasure and happiness. About a century later, Freud, stating that the Ego is not the master of its own house, throws the rational subject in a baffling place, with very little control of its action and decisions. Unlike Kant, Freud does not believe that the subject is inclined to pleasure and happiness. That which is beyond the Pleasure Principle is a basic Freudian notion, retaken by Lacan in 1959, the seventh year of his seminary, in order to deal with the ethics of psychoanalysis. Pure will, formulated by Kant to think the ethics of duty, becomes, hence, a major reference in what Lacan comes to call pure desire. Coming close to that which in the subject seems to point beyond the pleasure principle, Lacan, in an unexpected movement, sends the Kantian ethical proposition to the libertine philosophy of Sade, believing that Sade may help in his attempt of explicitating the subject's division, present yet veiled in Kant. That which points beyond the pleasure principle is, thus, fundamental for Lacan to build an ethics that places desire in the foreground. It is also what brings a serious problem to the ethics of psychoanalysis: its tragic dimension. Sophocles Antigone helps Lacan to demonstrate what can one come to when pure desire is taken to its extreme.