This book is widely known for its lucid account of the modern theory that sanity and insanity are not to be divided in a clear-cut way, but rather shade gradually into one another. Since this book deals mainly with the fundamental general principles of abnormal psychology, and these were already clearly formulated at the time it was first written in 1912, a considerable part of the text needs no amendment. The author has revised the introductory chapter on the historical development of the subject, and his preface explains the scope and purpose of those textual changes which he feels to be necessary. The contents include chapters on the history and psychological conception of mental disorder, the phenomena of mental disorder, dissociation, complexes, conflict, repression, manifestation of repressed complexes, projection, the irrationality of the insane, phantasy, and the significance of conflict.