In the first place I wish to express my gratitude to Doctors Frederick Peterson, William A. White, and Ernest Jones, for their many helpful suggestions in the translation of this work. This does not, however, imply that they are in any way responsible for the numerous barbarisms found in the translation, for this I, alone, ask the reader’s indulgence. For one thing, it must be borne in mind that, aside from the subject-matter, Freud is not easy to read, even in the original. Indeed, I feel quite certain that only those who have read the original will best appreciate the task of the translator. But no matter how devoid of literary excellencies this translation may be, it can at least claim one merit, to wit, it is a faithful reproduction of the author’s thoughts. This is really all that should be required of a translation. The chapters contained in this book were taken from three different volumes of the author’s works, published at different intervals within the last fifteen years. Although the first four chapters appear in the “Studien über Hysterie” which was published by Breuer and Freud,[1] still only the first chapter, “The Psychic Mechanism of Hysterical Phenomena,” was written conjointly by both authors. The authorship of the other three chapters belongs exclusively to Freud. The remaining six chapters of the book were taken from Freud’s Collection of Small Articles.[2] It was by no means an easy task to compile in a single limited volume Freud’s theories of the actual- and psychoneuroses. Freud’s views are not only new and revolutionary, being based on an entirely new psychology, but unless one is thoroughly familiar with their development one is apt to misunderstand them. To obviate this it was thought best to collect those chapters from the author’s works which fully illustrate his theories and at the same time show the gradual evolution of his psychology. That Freud’s views have undergone some changes, or rather modifications, within the last fifteen years we readily admit; but who will blame the surgeon for modifying or rejecting some technique of his operation, if after years of careful work he feels justified in so doing? Surely such an action merits applause rather than reproach. It was only after carefully investigating for years that Freud saw fit to change some of his views, yet nothing was really totally discarded. It is quite unnecessary to discuss here the whys and wherefores of the modifications in question, these are fully explained in the text. But it will not be mal à propos to say a few words concerning the technique of the treatment. For reasons given in the book the author has abandoned hypnotism and used the pressure procedure, but this in turn was given up because it was cumbersome for both doctor and patient and proved to be utterly needless.