Notwithstanding, we have the sentiment of liberty, and consequently, of responsibility. These are very curious illusions and very mysterious, but illusions none the less. Among those of which our life is composed, they are perhaps the most useful; they are even more,--they are necessary. We are not free, yet we cannot act except by believing ourselves free. If for a moment we actually ceased to believe in free will, we should at once cease to act altogether. In his book on _Duplicisme Humain_, M. Camille Sabatier has written: "Liberty is as inexplicable as it is certain." It is, in my opinion, the illusion of liberty that is as inexplicable as it is certain, and, I add, necessary. Where I agree fully with him is when he asserts that the matter presents "a mystery of our nature." He has attempted a most ingenious explanation, but which, I believe, leaves still standing the determinist objections, of which I have summarized several of the features. It is the eternal opposition of feeling and, not reason but reasoning. But it matters little whether they teach and adopt one or the other theory; that could have no influence upon the conduct of men or upon their judgments. Nor would it have any influence upon our manner of looking upon crime and the various infractions of the law and moral conventions. If men are free and consequently responsible, there need be no change in our judicial institutions. If men are not free, if they are irresponsible, there need still be no change, for a crime is a crime just the same,--always an anti-social act against the repetition of which it is necessary to protect ourselves. It even seems that the determinists, to whom I belong, would be inclined rather to a very severe repression. A philosophic doctrine is not necessarily a social doctrine. A determinist, doubtless, could not admit the idea of punishment, but he will readily admit that of repression. And it all comes to the same thing. We must live. Societies have no choice. But it is easy to understand why the physicians, who are almost all determinists, should have resolved not to take a stand upon questions of responsibility. That is not within the province of medicine, which should limit itself to declaring whether the subject is healthy or ill, and to caring for him if he is entrusted into its hands.