Almost at the outset it had been discovered that many patients presented clinical pictures that would not fit into existing diagnostic pigeon holes. Dr. George H. Kirby, whose skill and industry had made the most valuable contributions to the archives of the Institute, published in 1913 a brief paper in which he pointed out, not only that many cases with “catatonic” symptoms recovered, but also that clinically the behavior of stupor showed it to be related to manic-depressive insanity as well as dementia præcox. Dr. Hoch took up the problem at this point. Using Dr. Kirby’s material and adding to it his earlier observations as well as current cases, he endeavored to work out the essentials of the stupor reaction. It was his ambition to describe stupor not only in its psychiatric bearing but also as a life reaction. The significance of this task is to be realized only when one considers the general import of the functional psychoses. They are, biologically, failures of adaptation. The chronic and deteriorating cases give up the struggle permanently, while the temporary insanities lay bare the soul of man as he catches a glimpse of unreality but turns back to face the world as it is. When one realizes that emotional disturbances are characteristic of the benign psychoses, it is easy to imagine how much such studies may ultimately illuminate the problems of normal life. The technical value of this work to psychiatry is more immediate. Kraepelin laid the foundations for systematic classification with his dementia præcox and manic-depressive groups. But the rigidity of the latter, allegedly descriptive, term has confused the problem of classifying many benign psychoses. It was Hoch’s ambition to prove that, although elation and depression were the commonest mood anomalies in this group, they had no more theoretic importance than anxiety, distressed perplexity or apathy. These other moods, although less frequent, are just as characteristic of the psychoses in this group. In other words, the name “Anxiety-Apathy Insanity” would be as appropriate, theoretically, as Kraepelin’s term. In 1919 Hoch and Kirby published a report on the perplexity cases. This present book was designed to show that the symptom complex centering around apathy is as distinct as that which is recognized by all psychiatrists as mania with its predominant characteristic of elation. In 1917 ill health forced Dr. Hoch to resign from his official duties. He retired to California with the purpose of adding to psychiatric literature the fruits of his long experience and unrivaled judgment. His first task was this book. In the midst of this work came a sudden collapse. As I had been in close touch with his researches, coöperating in psychological speculations, and was free to devote some time to it, he asked shortly before his death that I complete the book. This obligation is incommensurate with the debt I owe for years of inspiration, tuition and criticism.