Psychology is the fruit of the application of the scientific method to mental processes; its subject matter consists of the observable phenomena of mind. Its application to sociology has produced an almost exclusive concentration on social functions; and while this has important uses, it does not furnish us with the clue we need to our sociological tasks. Mental functions, whether of the individual or of society, cannot be treated in the same way as chemical reactions. Chemical reactions are predetermined and invariable; human functions are dirigible. Those functions which ultimately govern and sustain human activity and determine human character are directed to more or less sharply recognised and chosen ends. It is indeed true that many of the processes which are concerned in the movement of life are, as Mr. Cooley has pointed out, unconscious and seemingly impersonal, such as those which account for the growth of tradition and the variations of language. Nevertheless, as Mr. Cooley himself very excellently shows in his illustration of the growth of a book in its author’s mind, even these unconscious and involuntary processes fall into line with a definitely fixed purpose of the mind.[6] The problem of sound social integration is not merely an affair of processes operating properly. For human powers may function, at least for a time, in a normal way even while they are being directed to mischievous and perverse ends. Modern Germany supplies an instance of unexampled attention to social processes; but it is not open to question that all this has been directed to a perverse and immoral end, and has (as the event has shown) culminated in catastrophe and confusion. Just so a man’s intellect may operate brilliantly; yet the man himself may be a thief. Psychology may claim that its business is a disinterested study of processes; and the claim is justly made. But the same claim cannot be made for sociology. The sociologist may indeed claim that he too is a scientist; and that his science like every other is empirical and not teleological. But the two claims are not parallel. Psychology deals with an _opus operatum_, the actual concrete mind as it is; whereas the assumption which underlies all sociology is that it is handling an _opus operandum_, a work still to be done, the production of a living and wholesome society. The teleological interest is necessarily supreme. This does not mean that sociology has not its empirical aspects; of course, it has; and these aspects are all important for the construction of a sound sociology. But we shall produce a mere torso of sociology if we suppose we can ignore the problem of ends. The relation of psychology to sociology is of much the same character as its relation to education or the relation of physiology to public health. Footnote 6: Charles Horton Cooley, _Social Process_, p. 16.