An inadequate index closes an unsatisfactory, though in many respects valuable, book. We note no fewer than twelve references to "Seneca," but none to "sex" or "shame;" sixteen to Hudson, but none to Freud, Janet, Prince, Adler, or Klarges. ERNEST JONES. AN INTRODUCTION TO SOCIAL PSYCHOLOGY. By William McDougall. Published by John W. Luce & Co., Boston, 1910. Although this book was published a few years ago, nevertheless it seems sufficiently important to the reviewer to have it brought prominently before psychopathologists. In the introduction McDougall reminds us that the instincts are the prime movers, the mental forces, the sources of energy, the springs of human action, the impulses and motives which determine the goals and course of all human activity, mental and physical. These instincts, being the fundamental elements of our constitution, must be clearly defined, and their history in the individual and the race determined. For this purpose, comparative and evolutionary psychology is necessary, for the life of the emotions and the play of motives in mental life are the least susceptible of introspective observation and description. "The old psychologising," says McDougall, "was like playing 'Hamlet' with the Prince of Denmark left out, or like describing steam-engines while ignoring the fact of the presence and fundamental role of the fire or other sources of heat." A knowledge of the constitution of the mind of man is a prerequisite for any understanding of the life of society in any or all of its many aspects. And this applies to psychopathology. I venture to assert that had certain individuals read and digested a book of this sort it might have been a prophylactic against an exclusively sexual conception of human conduct. The work is divided into two sections. Section one deals with the mental characteristics of man of primary importance for his life in society, while section two is concerned with the operation of the primary tendencies of the human mind in the life of societies. The successive chapters of the first section take up in order the following questions: the nature of instincts and their place in the constitution of the mind, the principal instincts and the primary emotions of man; some general or non-specific innate tendencies, the nature of the sentiments and the constitution of some of the complex emotions; the development of the sentiments; the growth of self-consciousness and of the self regarding sentiment; the advance to the higher plane of social conduct; and volition. In the second section the author considers the reproductive and the parental instincts, the instinct of pugnacity, the gregarious instinct, the instincts through which religious conceptions affect social life, the instincts of acquisition and construction, and there is a final chapter on imitation, play and habit.