The attempt to present and discuss Sartre's phenomenology without including the whole of his philosophical thought has to face more than the usual amount of difficulties presented by such a selective enterprise. They begin with the fact that a man of Sartre's versatility and vigor defies all conventional classifications. Thus, in studying Sartre the philosopher and phenomenologist, one must consider not only Sartre the novelist, the critic, the playwright, and the editor, but also the political figure. For since the war Sartre has become so involved in political action and in the theatre that one might well wonder whether he has not turned away from philosophy for good, were it not for the persistent announcements of a major philosophical work to appear in the near future. One might conceive of dividing up the task by concentrating on either the philosopher, the dramatist, or the novelist Sartre, as some of the more successful studies published thus far have approached him.¹ But Sartre's work is more than the sum of the output of his separate talents. There is a common source for all his multifarious activities. At their center is a unique philosophic concern. Some attempt to determine this core is therefore indispensable for any attempt to understand Sartre.