III. _The Causes of Prostitution:_--Prostitution as a Part of the Marriage System--The Complex Causation of Prostitution--The Motives Assigned by Prostitutes--(1) Economic Factor of Prostitution--Poverty Seldom the Chief Motive for Prostitution--But Economic Pressure Exerts a Real Influence--The Large Proportion of Prostitutes Recruited from Domestic Service--Significance of This Fact--(2) The Biological Factor of Prostitution--The So-called Born-Prostitute--Alleged Identity with the Born-Criminal--The Sexual Instinct in Prostitutes--The Physical and Psychic Characters of Prostitutes--(3) Moral Necessity as a Factor in the Existence of Prostitution--The Moral Advocates of Prostitution--The Moral Attitude of Christianity Towards Prostitution--The Attitude of Protestantism--Recent Advocates of the Moral Necessity of Prostitution--(4) Civilizational Value as a Factor of Prostitution--The Influence of Urban Life--The Craving for Excitement--Why Servant-girls so Often Turn to Prostitution--The Small Part Played by Seduction--Prostitutes Come Largely from the Country--The Appeal of Civilization Attracts Women to Prostitution--The Corresponding Attraction Felt by Men--The Prostitute as Artist and Leader of Fashion--The Charm of Vulgarity. IV. _The Present Social Attitude Towards Prostitution:_--The Decay of the Brothel--The Tendency to the Humanization of Prostitution--The Monetary Aspects of Prostitution--The Geisha--The Hetaira--The Moral Revolt Against Prostitution--Squalid Vice Based on Luxurious Virtue--The Ordinary Attitude Towards Prostitutes--Its Cruelty Absurd--The Need of Reforming Prostitution--The Need of Reforming Marriage--These Two Needs Closely Correlated--The Dynamic Relationships Involved. CHAPTER VIII. THE CONQUEST OF THE VENEREAL DISEASES. The Significance of the Venereal Diseases--The History of Syphilis--The Problem of Its Origin--The Social Gravity of Syphilis--The Social Dangers of Gonorrhoea--The Modern Change in the Methods of Combating Venereal Diseases--Causes of the Decay of the System of Police Regulation--Necessity of Facing the Facts--The Innocent Victims of Venereal Diseases--Diseases Not Crimes--The Principle of Notification--The Scandinavian System--Gratuitous Treatment--Punishment For Transmitting Venereal Diseases--Sexual Education in Relation to Venereal Diseases--Lectures, Etc.--Discussion in Novels and on the Stage--The "Disgusting" Not the "Immoral". CHAPTER IX. SEXUAL MORALITY.