The book begins with an exhaustive examination of the biological mechanics of reproduction, tracing cellular division, the evolution of species, and the cellular basis of heredity. Forel details how germinal cells carry ancestral traits through physical and chemical laws, establishing the biological framework from which all human development originates. The discussion then moves to the physical conditions of human coitus, detailing the anatomy of the male and female reproductive systems, the physiology of erection and ejaculation, and the complex process of pregnancy from conception to birth.
From these biological foundations, the author explores the sexual appetite in both men and women, examining how primal instincts manifest as conscious desire, emotional attachment, and psychological need. Forel contrasts the active, varied drive of the male with the more passive, maternal, and constant nature of the female, highlighting the profound psychological differences that shape their interactions. These primal instincts naturally irradiate into higher human emotions, including love, jealousy, and the complex social bonds that form the basis of the family unit.
Moving into ethnology and history, the text investigates the origins of marriage, dismissing theories of primitive promiscuity in favor of a natural evolution toward family structures rooted in the protection of offspring. Forel surveys the diverse forms of marriage, customs of attraction, and the historical role of sentiment versus calculation in sexual selection. He emphasizes that the family, derived from the higher mammalian instinct to protect the young, is the fundamental building block of human society and the primary vehicle for the transmission of social duty.
Addressing the dark side of human sexuality, the author dedicates substantial analysis to sexual pathology, covering anatomical anomalies, venereal diseases, reflex disorders, and psychological deviations such as sadism, masochism, and inversion. He examines the catastrophic impact of alcohol on the germ cells—a phenomenon he terms blastophthoria—which deposits hereditary stigmata across generations. The text also investigates the role of suggestion, amorous intoxication, and the destructive pressures of money, property, and prostitution on human relationships.
Finally, Forel addresses the wider social implications of the sexual question, examining its relationship with civil and penal law, medicine, public hygiene, and the regulation of conception. He discusses the influence of environment, rank, and religion on sexual life, offering medical and hygienic advice for marriage and pregnancy. The work concludes with utopian yet pragmatic reflections on the ideal marriage of the future, advocating for a rational, scientific approach to sexual reform that elevates the physical and mental faculties of future generations through education and the elimination of ignorance and prudery.
