The Primitive View of Women--As a Supernatural Element in Life--As Peculiarly Embodying the Sexual Instinct--The Modern Tendency to Underestimate the Sexual Impulse in Women--This Tendency Confined to Recent Times--Sexual Anæsthesia--Its Prevalence--Difficulties in Investigating the Subject--Some Attempts to Investigate it--Sexual Anæsthesia Must be Regarded as Abnormal--The Tendency to Spontaneous Manifestations of the Sexual Impulse in Young Girls at Puberty. II. Special Characters of the Sexual Impulse in Women--The More Passive Part Played by Women in Courtship--This Passivity Only Apparent--The Physical Mechanism of the Sexual Process in Women More Complex--The Slower Development of Orgasm in Women--The Sexual Impulse in Women More Frequently Needs to be Actively Aroused--The Climax of Sexual Energy Falls Later in Women's Lives than in Men's--Sexual Ardor in Women increased After the Establishment of Sexual Relationships--Women Bear Sexual Excesses Better than Men--The Sexual Sphere Larger and More Diffused in Women--The Sexual Impulse in Women Shows a Greater Tendency to Periodicity and a Wider Range of Variation. III. Summary of Conclusions. APPENDIX A. The Sexual Instinct in Savages. APPENDIX B. The Development of the Sexual Instinct. INDEX OF AUTHORS. INDEX OF SUBJECTS. ANALYSIS OF THE SEXUAL IMPULSE. Definition of Instinct--The Sexual Impulse a Factor of the Sexual Instinct--Theory of the Sexual Impulse as an Impulse of Evacuation--The Evidence in Support of this Theory Inadequate--The Sexual Impulse to Some Extent Independent of the Sexual Glands--The Sexual Impulse in Castrated Animals and Men--The Sexual Impulse in Castrated Women, after the Menopause, and in the Congenital Absence of the Sexual Glands--The Internal Secretions--Analogy between the Sexual Relationship and that of the Suckling Mother and her Child--The Theory of the Sexual Impulse as a Reproductive Impulse--This Theory Untenable--Moll's Definition--The Impulse of Detumescence--The Impulse of Contrectation--Modification of this Theory Proposed--Its Relation to Darwin's Sexual Selection--The Essential Element in Darwin's Conception--Summary of the History of the Doctrine of Sexual Selection--Its Psychological Aspect--Sexual Selection a Part of Natural Selection--The Fundamental Importance of Tumescence--Illustrated by the Phenomena of Courtship in Animals and in Man--The Object of Courtship is to Produce Sexual Tumescence--The Primitive Significance of Dancing in Animals and Man--Dancing is a Potent Agent for Producing Tumescence--The Element of Truth in the Comparison of the Sexual Impulse with an Evacuation, Especially of the Bladder--Both Essentially Involve Nervous Explosions--Their Intimate and Sometimes Vicarious Relationships--Analogy between Coitus and Epilepsy--Analogy of the Sexual Impulse to Hunger--Final Object of the Impulses of Tumescence and Detumescence.