events arising in the ordinary course of nature, — events, moreover, the conditions of whose happening or non-happening from one moment to another, lie certainly in large part in the physical world. Not only this; they are events of such tremendous practical moment to us that the control of these conditions on a large scale would be an achievement compared with which the control of the rest of physical nature would appear comparatively insignificant. All natural sciences aim at practical prediction and control, and in none of them is this more the case than in psychology to-day. We live surrounded by an enormous body of persons who are most definitely interested in the control of states of mind, and incessantly craving for a sort of psychological science which will teach them how to act. What every educator, every jail-warden, every doctor, every clergyman, every asylum-superintendent, asks of psychology is practical rules. Such men care little or nothing about the ultimate philosophic grounds of mental phenomena, but they do care immensely about improving the ideas, dispositions, and conduct of the particular individuals in their charge.
Now out of what may be called the biological study of human nature there has at last been precipitated a very important mass of material strung on a guiding conception which already to some degree meets these persons' needs. The brain-path theory based on reflex action, the conception of the human individual as an organized mass of tendencies to react mentally and muscularly on his environment in ways which may be either preservative or destructive, not only helps them to analyze their cases, but often leads them to the right remedy when perversion has set in. How much more this conception may yet help them these men do not know, but they indulge great hopes. Together with the physiologists and naturalists they already form a band of workers, full of enthusiasm and confidence in each other, and are pouring in materials about human nature so copious that the entire working life of a student may easily go to keeping abreast of the tide. The 'psychical researchers,' though kept at present somewhat out in the cold, will inevitably conquer the recognition which their labors also deserve, and
