Book excerpt: This book is intended primarily for those readers who have had no professional training in either Medicine or Psychology, but who are anxious to keep themselves abreast of modern thought in these departments of knowledge. At the same time I hope it may prove serviceable to professional students of these subjects as a preliminary survey of the ground they will have to cover should they desire to specialize in psychotherapies or in the psychology of the abnormal. The topics discussed have been dealt with only in outline. My endeavour has been to state the general principles on which modern conceptions in the Psychology of Medicine are based and to avoid as far as possible all detail which is unncessary for comprehension of these principles.