All those portions of the book which are of medical or medico-legal interest, including most of the cases, have appeared during the last three years in the _Alienist and Neurologist_, the _Journal of Mental Science_, the _Centralblatt für Nervenheilkunde_, the _Medico-legal Journal_, and the _Archivo delle Psicopatie Sessuale_. The cases, as they appear in the present volume, have been slightly condensed, but nothing of genuine psychological interest has been omitted. Owing to some delay in the publication of the English edition of the work, a German translation by my friend, Dr. Hans Kurella, editor of the _Centralblatt für Nervenheilkunde_, has already appeared (1896) in the _Bibliothek für Sozialwissenschaft_. The German edition contains some matter which has finally been rejected from the English edition as of minor importance; on the other hand, much has been added to the English edition, and the whole carefully revised. I have only to add that if it may seem that I have unduly ignored the cases and arguments brought forward by other writers, it is by no means because I wish to depreciate the valuable work done by my predecessors in this field. It is solely because I have not desired to popularize the results previously reached, but simply to bring forward my own results. If I had not been able to present new facts in what is perhaps a new light, I should not feel justified in approaching the subject of sexual inversion at all. HAVELOCK ELLIS. CONTENTS CHAPTER I. INTRODUCTION. Homosexuality Among Animals--Among the Lower Human Races--The Albanians--The Greeks--The Eskimos--The Tribes of the Northwest United States--Homosexuality Among Soldiers in Europe--Indifference Frequently Manifested by European Lower Classes--Sexual Inversion at Rome--Homosexuality in Prisons--Among Men of Exceptional Intellect and Moral Leaders--Muret--Michelangelo--Winkelmann--Homosexuality in English History--Walt Whitman--Verlaine--Burton's Climatic Theory of Homosexuality--The Racial Factor--The Prevalence of Homosexuality Today. CHAPTER II. THE STUDY OF SEXUAL INVERSION. Westphal--Hössli--Casper--Ulrichs--Krafft-Ebing--Moll--Féré--Kiernan-- Lydston--Raffalovich--Edward Carpenter--Hirschfeld. CHAPTER III. SEXUAL INVERSION IN MEN. Relatively Undifferentiated State of the Sexual Impulse in Early Life--The Freudian View--Homosexuality in Schools--The Question of Acquired Homosexuality--Latent Inversion--Retarded Inversion--Bisexuality--The Question of the Invert's Truthfulness--Histories. CHAPTER IV. SEXUAL INVERSION IN WOMEN. Prevalence of Sexual Inversion Among Women--Among Women of Ability--Among the Lower Races--Temporary Homosexuality in Schools, etc.--Histories--Physical and Psychic Characteristics of Inverted Women--The Modern Development of Homosexuality Among Women. CHAPTER V. THE NATURE OF SEXUAL INVERSION.