In the late 19th and early 20th centuries, Austrian Sigmund Freud, a 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 The Ego and the Id (Das Ich Und Das Es), written in 1923, Freud articulates his theories on the psychodynamics of the Ego, the Superego, and the Id, which were crucial for the evolution of psychoanalytic theory.

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