Until the 18th century, the dominant view was that there was only one sex - the male. The female body was understood as an inverted, less perfect version of the male body, as evidenced by medical texts, illustrations, and cultural practices.

During the 18th century, the concept of two fundamentally different sexes emerged, linked to social changes, new scientific discoveries, and the development of modern gender roles. The emphasis on biological differences was used to reinforce existing social order.

The book demonstrates how cultural norms and scientific discourse shape our perception of gender, calling for a questioning of the seemingly natural categories of 'male' and 'female' and recognition of human experiences beyond this binary order.