The first edition of this work was published more than twelve years ago. The book explains in nontechnical language the essentials of modern psychology and the principles of psychiatry and mental hygiene. The usefulness of the previous edition prompted the development of the present volume, which includes new chapters on emotion, fear and anger and incorporation of the ideas of psychosomatic medicine. There is also attention to special problems created by the war. Another addition to the work is an appendix providing a series of questions on the individual chapters. The book is well printed, easily readable and can be recommended to physicians as a work which they, in turn, can confer on patients who need therapeutic literature.