Definition of Auto-erotism--Masturbation only Covers a Small Portion of the Auto-erotic Field--The Importance of this Study, especially To-day--Auto-erotic Phenomena in Animals--Among Savage and Barbaric Races--The Japanese _rin-no-tama_ and other Special Instruments for Obtaining Auto-erotic Gratification--Abuse of the Ordinary Implements and Objects of Daily Life--The Frequency of Hair-pin in the Bladder--The Influence of Horse-exercise and Railway Traveling--The Sewing-machine and the Bicycle--Spontaneous Passive Sexual Excitement--_Delectatio Morosa_--Day-dreaming--_Pollutio_--Sexual Excitement During Sleep--Erotic Dreams--The Analogy of Nocturnal Enuresis--Differences in the Erotic Dreams of Men and Women--The Auto-erotic Phenomena of Sleep in the Hysterical--Their Frequently Painful Character. II. Hysteria and the Question of Its Relation to the Sexual Emotions--The Early Greek Theories of its Nature and Causation--The Gradual Rise of Modern Views--Charcot--The Revolt Against Charcot's Too Absolute Conclusions--Fallacies Involved--Charcot's Attitude the Outcome of his Personal Temperament--Breuer and Freud--Their Views Supplement and Complete Charcot's--At the Same Time they Furnish a Justification for the Earlier Doctrine of Hysteria--But They Must Not be Regarded as Final--The Diffused Hysteroid Condition in Normal Persons--The Physiological Basis of Hysteria--True Pathological Hysteria is Linked on to almost Normal States, especially to Sex-hunger. III. The Prevalence of Masturbation--Its Occurrence in Infancy and Childhood--Is it More Frequent in Males or Females?--After Adolescence Apparently more Frequent in Women--Reasons for the Sexual Distribution of Masturbation--The Alleged Evils of Masturbation--Historical Sketch of the Views Held on This Point--The Symptoms and Results of Masturbation--Its Alleged Influence in Causing Eye Disorders--Its Relation to Insanity and Nervous Disorders--The Evil Effects of Masturbation Usually Occur on the Basis of a Congenitally Morbid Nervous System--Neurasthenia Probably the Commonest Accompaniment of Excessive Masturbation--Precocious Masturbation Tends to Produce Aversion to Coitus--Psychic Results of Habitual Masturbation--Masturbation in Men of Genius--Masturbation as a Nervous Sedative--Typical Cases--The Greek Attitude toward Masturbation--Attitude of the Catholic Theologians--The Mohammedan Attitude--The Modern Scientific Attitude--In What Sense is Masturbation Normal?--The Immense Part in Life Played by Transmuted Auto-erotic Phenomena. APPENDIX A. The Influence of Menstruation on the Position of Women. APPENDIX B. Sexual Periodicity in Men. APPENDIX C. The Auto-erotic Factor in Religion. INDEX. DIAGRAMS. THE EVOLUTION OF MODESTY. I. The Definition of Modesty--The Significance of Modesty--Difficulties in the Way of Its Analysis--The Varying Phenomena of Modesty Among Different Peoples and in Different Ages.