Otto Weininger begins by challenging the traditional binary division of living things into purely male or female categories, arguing instead for a permanent bisexual constitution in all organisms. Building upon embryological observations of sexually neutral embryonic stages, he demonstrates that sexual differentiation is never complete and that vestigial characteristics of the opposite sex always persist within every individual. Expanding this biological premise from the reproductive organs to every cell in the body, Weininger introduces the concepts of arrhenoplasm and thelyplasm to explain the countless gradations of masculinity and femininity found across bodily tissues and metabolic processes.
Transitioning from biology to the laws of sexual attraction, Weininger formulates a mathematical and empirical principle of affinity. He posits that true sexual union requires the coming together of a complete male and a complete female element, distributed in complementary proportions between two individuals. This law of sexual complements explains why personal tastes in the opposite sex are remarkably specific and reciprocal, and why unions based on maximum suitability yield the strongest offspring. He extends this comparative analysis to the vegetable kingdom, drawing parallels between human sexual affinity and the phenomena of heterostylism observed in plants by Charles Darwin.
The inquiry then addresses sexual inversion and homosexuality, rejecting the notion that these inclinations are merely acquired habits or neuropathic degeneration. Instead, Weininger classifies homosexuals and inverts as intermediate sexual forms whose internal constitutions require complementary partners from their own side of the sexual spectrum. He argues that bisexuality is a latent universal condition, noting that passionate attachments during adolescence frequently display this ambivalence before maturity establishes distinct behavioral patterns.
Applying these physiological principles to psychology and the science of character, Weininger explores the differences between male and female consciousness. He differentiates the articulated, conscious life of the male from the unarticulated, instinctive nature of the female, associating the former with continuous memory, logic, and the capacity for genius. The female, living primarily through the unconscious immediacy of sexual impulses and lacking continuous memory, operates outside the strict demands of logical identity and ethical responsibility. This structural deficiency in the unarticulated female mind accounts for the absence of original genius in philosophy, science, and the arts among women.
Finally, Weininger examines the historical and contemporary movements for the emancipation of women. He maintains that genuine intellectual freedom and the craving for creative power are manifestations of masculinity present only in sexually intermediate women. True female nature, he argues, possesses neither the desire nor the capacity for intellectual emancipation, viewing such agitation as an artificial departure from its biological purpose. Through these rigorous deductions, the text lays the theoretical groundwork for a new science of character based on the immutable realities of sexual polarity.
