There is, however, another side to this whole question. _The notion of a subconscious has proved useful in certain fields of practical psychology, and more especially in psychiatry and psychotherapeutics; and in matters of practice utility is a sufficient justification._ Science cannot ask the physician to give up a theory which works. She can only point out that present utility is no test of ultimate truth,—there were plenty of useful inventions in the days when the physics of heat was dominated by the theory of caloric, and the physics of light by the theory of emission!—and that nobody has ever observed, or can ever observe, the subconscious at work; the wonderful things that it does testify rather to their reporter’s thought and imagination, to his conscious ingenuity in explaining, than to the scientific reality of the subconscious itself. § 78. =Conclusion.=—So we are at an end; and as you look back over the chapters of the book, you will have your own thoughts about the work done,—about your change of attitude from common sense to psychology, about the nature of mind, when mind is regarded from the scientific point of view, about the difficult or unsatisfactory places in psychology. The author has no wish to disturb these thoughts; every student must sum things up for himself, as every student, if he is to get the scientific point of view, must rely on his own thinking from the beginning (p. 36); for the kingdom of science is not in word but in power. There are, nevertheless, a few considerations that may be set down here, not as a summary made for you by the author, but simply as a general supplement to your own conclusions. Realise, then, first of all, that _there is nothing in the whole wide world that cannot be psychologised_. Sound and light and heat, law and language and morals, “the whole choir of heaven and furniture of earth,” all alike become subject-matter of psychology if we regard them from the psychological standpoint, as they are in man’s experience (p. 9). The range of psychology is the range of that experience, and nothing more narrow. The psychological point of view is logically coordinate with the point of view of the physical sciences; these describe the world with man left out, psychology describes the world with man left in; but the psychologist surveys the broader field.