Recollect, Gentlemen, that I have not undertaken to prove the existence of God, by making appeal to the authority of men of science. All I have sought to do has been to destroy a prejudice. They tell us, and scream it at us, that the best naturalists become atheists. This is not true, as I think I have shown. There do exist atheists who cultivate the natural sciences,--no doubt of the fact. But even though half the whole number of naturalists were atheists, inasmuch as other naturalists, and those some of the greatest, find in their studies new motives to adoration, we are forced to the conclusion, that the true cause why these savants repudiate religion has nothing to do with their science. We shall come to be more strongly confirmed in this opinion, if we pass now from the question of fact to considerations of sound reason. The weakness of the human mind leads it to forget the facts with which it is not occupied. All special culture of the intellect risks consequently the paralyzing a part of our faculties. Hegel, lost in abstractions, persuades himself that he will be able to construct by pure reasoning the history of nature and that of the human race. A geometrician, who no longer saw in the world anything but theorems and demonstrations, asked, after the representation of a dramatic masterpiece, "And what does that prove?" A physiologist absorbed in the study of sensible phenomena says: "Where is that soul they talk of? I have never seen it." These are phenomena of the same order. This infirmity of the mind, which leads certain savants to think that the ordinary subject of their studies is everything, must not be imputed to science. A man accustomed to the exclusive observation of material phenomena, may become a materialist by the effect of his mental habits, and this really happens, in fact, in too many instances; but the study in itself is not responsible for this result. Let us endeavor to prove this, by clearly defining the object of the natural sciences. When the matter of a phenomenon is given to us, the understanding proposes to itself three questions: 1. How does the fact manifest itself? what is the mode of its existence? The answer gives us the law of the phenomenon. Bodies fall to the ground at a determined rate of speed: the determination of this rate is the law of their fall. 2. What is the real effective power which produces the phenomenon? This is the inquiry after the cause. 3. What is the intention which presided at the production of the phenomenon? This is the search after the object, which philosophers call the final cause.