I shall not here give a critical presentation of the arguments by which systems such as these have established the absence of freedom in man. In our present need, a single remark will suffice, and will permit us, I believe, to cut the discussion short. A great German philosopher, who had conceived science and reality, which is the object of science, in such a way as to preclude the possibility of finding in reality a place for man's freedom, noticed that freedom, in spite of all the difficulties which science encounters in accounting for it, corresponds and answers to an invincible certitude in our soul, invincible because a postulate of our moral conscience. That is to say, that whatever our scientific theories and ideas, we have a conscience which imposes a law upon us,--a law which, though not promulgated and sustained by any external force, or rather because of it, compels us in a manner which is absolute. This law is the moral law. It requires no speculative demonstration. The scrutiny of philosophers might not be helpful to it. It rises spontaneously and naturally from the intimate recesses of our spirit; and it demands from our will, from the will of the most uncouth man, an unconditional respect. What sense would there be in the word duty, if man were able to do only those things which his own nature, or worse still, nature in general, compelled him to do? The existence of duty implies a power to fulfil it. And the certitude of our moral obligations rests on the conviction that we have within us the power to meet them. We can answer the call of duty because we are free. This consideration, important as it is, cannot however be considered as sufficient. For this moral conscience, this certitude with which the moral conscience affirms the existence of an unavoidable duty, might also be an illusion determined in us by natural causes. Nothing hinders us from thinking thus, and surely there is no contradiction implied in this explanation, which in fact because of its possibilities is offered by the philosophers of materialism. But the need of liberty is not solely felt when we strive to conceive our moral obligations; freedom is not only the ground for existence, the _raison d'être_ of moral law, as Kant thought--for he is the philosopher to whom I alluded above;--no! freedom is the condition of the entire life of the spirit. And the materialist who, having destroyed liberty as a condition of moral conduct, believes that he is still able to think, that his intellectual activity can proceed undisturbed after his faith in the objective value and in the reality of moral laws has been abandoned, such a materialistic thinker is totally mistaken. For without freedom, man not only is unable to speak of duty, but he cannot speak at all,--not even of his materialistic views. This is the same as saying that the negation of liberty is unthinkable.