of modern times an invaluable protection and an uninterrupted series of scientific gifts. The photometry of Lambert led not only to the methods of modern technical photometry but also to the measurement of our sensations of light, while the law of relativity of sensations had been—before Fechner—established for lights by Bouguer, Masson, Arago, Herschel, and Steinheil. The study of the errors of observation in physics and astronomy has led not only to the science of physical measurements, but also to that of psychological measurements. Newton, Young, and Maxwell began not only the science of ether vibrations, but also the science of sensations of color. The laws of mechanics apply not only to inanimate objects but also to the results of our own volitions. In fact, in every department of psychology, progress has been and still is closely dependent on the achievements of physics and technology.
Psychology has not only received most of its methods and much of its material from physics; it has for the first time in history reached through physics a definite conception of its own problem. The older psychology and philosophy had always maintained the necessity of directly investigating the facts of consciousness. The standpoint was simple enough, but, as no scientific methods of doing so were developed, the whole problem remained vague and unsatisfactory. Among the proposals for a better state of affairs was that of first investigating the nervous system and then deducing psychological laws therefrom. The brain was to be accurately mapped out into faculties, the paths of nervous currents were to be traced along various fibers, and the interaction of nervous molecules was to be known in every particular; it was even expected that various cells could be cut out, with a memory or a volition snugly inclosed in each. In other words, there was to be no psychology except on the basis of a fully developed brain physiology. Unfortunately, very little has been ascertainable concerning the finer functions of the nervous system. Aside from a general knowledge that the cerebellum has to do with co-ordination of movements, the convolutions of Broca have to do with speech, and similar facts, nothing of even the remotest psychological bearings has been discovered concerning the functions of the brain. The roseate hopes of those who expected a new psychology out of a "physiology of mind" were totally disappointed. In the effort for something new, however, the psychologist supplied the data concerning the "molecular movements" in the brain out of his own imagination; the familiar facts of mind were retold in a metaphorical language of "nerve currents," "chemical transformation," etc., of which not one particle had a foundation in fact. The physiology of mind started with an impossibility and ended with an absurdity.
