This book is the first of the four volumes promised by the author on the principles of psychophysiology. It embraces the parts dealing with the definition of psychology, with psychophysiological methods of investigation and with the whole field of perception. That the author is friendly toward the Freudian type of psychology is made clear in his review of general psychological knowledge where he states “By thus laying stress upon the problem of motivation, the psychoanalysts have given psychology a tremendous impetus in a direction along which it must travel progressively if it is to be of maximum human utility. The Freudian emphasis