Before passing on to an examination of Bergson's treatment of Evolution, we must consider his discussion of the problem of Freedom of the Will. Few problems which have occupied the attention of philosophers have been more discussed or have given rise to more controversy than that of Freedom. This is, of course, natural as the question at issue is one of very great importance, not merely as speculative, but also in the realm of action. We ask ourselves: "Are we really free?" Can we will either of two or more possibilities which are put before us, or, on the other hand, is everything fixed, predestined in such a way that an all-knowing consciousness could foretell from our past what course our future action would take? The study of the physical sciences has led to a general acceptance of a principle of causality which is of such a kind that there seems no place in the universe for human freedom. Further, there is a type of psychology which gives rise to the belief that even mental occurrences are as determined as those of the physical world, thus leaving no room for autonomy of the Will. But even when presented with the arguments which make up the case for physical or psychological determinism, the spirit of man revolts from it, refuses to accept it as final, and believes that, in some way or other, the case for Freedom may be maintained. It is at this point that Bergson offers us some help in the solution of the problem, by his Essai sur les donnees immediates de la conscience, better described by its English title Time and Free Will.