If we trace the history of human thought, we find that _the scientific attitude, as we have here described it, has emerged very slowly from that mixed medley of superstition and knowledge and belief and practical interest for which we have no better name than_ =common sense=. How common sense has been constituted, and how science has gradually worked its way to an independent position,—these are interesting questions; but it is plain that we cannot enter upon them in a primer of one special science. Some references for further reading will be given at the end of the chapter. Meanwhile, the important thing is to understand clearly the aims and limitations of science. Science aims at truth; it deals with facts, with the nature of things given, not with values or meanings or uses; and it deals with these materials impersonally and disinterestedly. The student of science who fails to grasp the scientific point of view will fail also to get the perspective of a scientific text-book; he will not see the wood for the trees; and he will be disappointed with what science has to offer him; he will want to know the use of all this knowledge, while science has no regard for use. =The laws of psychology may be put to very many uses=, in business, in education, in legal procedure, in medicine, in the ministrations of religion; but such uses are, from the psychologist’s point of view, by-products of his science; just as the nautical almanac is a by-product of astronomy, or the safety-match a by-product of chemistry, or the stamping-out of malaria a by-product of biology. These practical results may be immensely important for everyday life; but science, in its impersonal and disinterested search for facts, makes no difference between one fact and another. § 2. =The Subject-matter of Psychology.=—Psychology is the science of mind. What, then, is mind? Everybody knows that, you will say, just as everybody knows what is matter. Everybody knows, yes, in terms of common sense; but we have seen that common sense is not science. Besides, common sense is not articulate; it cannot readily express itself; and it is a little afraid of plain statements. Close this book, now, and write down what _you_ take mind to be; give yourself plenty of time; when you have finished, go over what you have written, and ask yourself if you really know what all the words and phrases mean, if you can define them or stand an examination on them; the exercise will be worth while.