In the late 19th and early 20th centuries, the Austrian Sigmund Freud, physiologist and psychiatrist, laid the foundations of psychoanalysis as a therapeutic method through his studies and revolutionized the way modern man perceives concepts such as consciousness and sexuality.

In the work Three Essays on the Theory of Sexuality (Drei Abhandlungen zur Sexualtheorie, First Edition 1905), Freud attempts to answer the question of whether the deviations of the sexual drive in terms of object and aim stem from innate tendencies or are acquired from life influences.

Drawing from everyday medical experience, which is reinforced by the results of psychoanalytic research, Freud argues that the onset of adolescence marks the beginning of changes that guide childhood sexual life to its definitive normal formation.

[Excerpt from the text on the back cover of the edition]