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141 less for erecting a speculative psychology upon their foundation."

My conclusion, therefore, is that psychology is not a natural science either in subject matter or in method, and that there is no reason for affiliating it with natural science. Its task is to study the facts of mental life, and its fundamental method is that of introspection. Now it is conceivable, of course, that it should cut loose from its historical association with philosophy and proclaim its independence. But there is no good reason why this should be done. Indeed, it is to the interest of both parties that the old friendly relations be continued. Philosophy needs the companionship and example of psychology to do fruitful work, and psychology cannot fail to benefit by such association herself.

By philosophy we here mean the subjects taught under that name by the philosophical departments of our universities, logic, æsthetics, ethics, epistemology, and metaphysics. All these are mental sciences, all are primarily concerned with mind. Psychology is indispensable to these fields of investigation, so indispensable that many writers have been tempted to regard them all as branches of psychology. Though they are not that, psychology may be said to hold the key to the situation. Not one of them can neglect psychology with impunity. Logic, æsthetics, ethics, and the theory of knowledge are interested in mind, and it is essential that they understand the mind. And metaphysics, though it is interested in all the facts of existence, in the physical as well as the mental realms, has a particularly vital interest in the inner world. Its concepts, methods, ideals, and evaluations are products of the human mind, and it must reckon with the source from which they spring. All these subjects are so intimately bound up with psychology that separation would mutilate them all. The close relation existing between them has its practical consequences also. The students in a department of philosophy cannot afford to neglect the study of mental life: ignorance of psychology will make itself felt in the work of the related subjects. And the needs of the department would not be satisfied by courses in psychophysics and physiological psychology given by natural scientists.