It is easy to see that all the positive sciences are differently related to these two parts of philosophy. None of them, for instance, can dispense with the first, with the criticism of our faculty of knowing and of our means of reasoning, under penalty of mistaking the worth of its own hypotheses, and even the regularity of its processes. It is clear that a physicist cannot dispense with correct syllogisms or with vigilance against illusions of the senses and other errors of method. But, on the other hand, no savant would accept the yoke of any metaphysic whatever which should come to him _a priori_ to dictate to him its conclusions. Upon indications of this nature he desires to form hypotheses and make new experiments; but, as a savant, he will never pronounce before that supreme and decisive consultation of facts. It is exactly the same with the relations of dogmatics to philosophy. It will have recourse to it for all that regards the theory of knowledge in general and the theory of religious knowledge in particular. Like every other science it needs to ascertain the scope of its instrument in order that it may be under no illusion as to the worth of the work it accomplishes. But also, like every other science, it has the right and the duty to challenge and neglect all general metaphysic which, flowing from another principle than that of the Christian religion, would dictate to it articles of faith or rules of morality. Let it not be said that every theory of knowledge soon begets a metaphysic in its own image. We know theories which deny the very possibility of metaphysics, and it is a question whether a truly Christian dogmatic accommodates itself to it better than any other theory. It may be maintained in fact that the act of faith which is the expression of the conservating energy of the ego and the principle of all religion is accomplished all the more freely when there is no knowledge, properly speaking, there to hinder it. A common prejudice requires that we should have metaphysics as a support to religion. It is on religion, on the contrary, that metaphysics and ethics rest. Man did not become religious when he heard that there were gods; he only had the idea of God and believed in Him because he was religious. Mystery was the natural cradle of piety. Faith is much less an acquisition of knowledge than a means of salvation and a source of strength and life. It is one thing to speculate on the universal problem; it is another to place one's self by the heart in a living relation of trust, of fear, or of love to the mysterious Being on whom all other beings depend. Religion may possibly be under the necessity of ending in a metaphysic, but a metaphysic does not necessarily end in religion, for there are some kinds of metaphysic which either exclude religion or render it impossible.