The aim of this volume is to present clearly the accepted facts of psychology. Throughout, emphasis has been placed upon fact rather than theory. Where theories conflict, the better one has been chosen, the others merely neglected. This may seem dogmatic in places, but in a text dogmatism is preferable to confusion. The point of view is on the whole functional; more attention is given to what mind does than to what it is. With this goes an emphasis upon the outward manifestations of consciousness and upon the behaviour of others to the subordination of the individual consciousness. Nevertheless, use is made of the results of structural psychology wherever they throw light upon function or are interesting for themselves. The position, it is hoped, combines the advantages of the rival schools. The content of a text-book in psychology is sufficiently agreed upon to require no comment. The general practice has been followed of introducing a brief exposition of the nervous system and its function. This is done with a full appreciation that it is no part of the task of the psychologist to teach neurology, but with the conviction that the beginning student in psychology is not likely to have acquired the knowledge elsewhere. In this treatment as little detail of structure has been given as is compatible with an understanding of function. Large use has been made of the hypothesis of the synapse. Its convenience in explaining habit and association outweighs any scruples about its final position in physiology. For the rest, I have deviated from traditional usage only in introducing rather more of the results of recent experiment. A body of knowledge has been developing in connection with memory and action that seems ripe for embodiment in a text. Similar considerations have led to the introduction of chapters on fatigue and on the transfer of training.