What do we mean by a mind? This is a question to which one can scarcely give an intelligent answer unless one has exercised one's faculty of philosophic reflection. And upon what sort of evidence does one depend in establishing the existence of minds other than one's own? This has been discussed at length in Chapter X, and the problem is certainly a metaphysical one. And if we believe that the Divine Mind is not subject to the limitations which confine the human, how shall we conceive it? The question is an important one. Some of the philosophers and theologians who have tried to free the Divine Mind from such limitations have taken away every positive mark by which we recognize a mind to be such, and have left us a naked "Absolute" which is no better than a labeled vacuum. Moreover, we cannot refuse to consider the question of God's relation to the world. This seems to lead back to the broader question: How are we to conceive of any mind as related to the world? What is the relation between mind and matter? If any subject of inquiry may properly be called metaphysical, surely this may be. We see, then, that there is little wonder that the thoughtful consideration of the facts and doctrines of religion has taken its place among the philosophical sciences. Aesthetics has been called applied psychology; and I think it is scarcely too much to say that we are here concerned with applied metaphysics, with the attempt to obtain a clear understanding of the significance of the facts of religion in the light of those ultimate analyses which reveal to us the real nature of the world of matter and of minds. CHAPTER XXI PHILOSOPHY AND THE OTHER SCIENCES 78. THE PHILOSOPHICAL AND NON-PHILOSOPHICAL SCIENCES.--We have seen in the preceding chapters that certain of the sciences can scarcely be cultivated successfully in complete separation from philosophy. It has also been indicated in various places that the relation of other sciences to philosophy is not so close. Thus, the sciences of arithmetic, algebra, and geometry may be successfully prosecuted by a man who has reflected little upon the nature of numbers and who has never asked himself seriously what he means by space. The assumptions which he is justified in making, and the kind of operations which he has the right to perform, do not seem, as a rule, to be in doubt.