The "Three Essays on the Theory of Sexuality", along with the "Interpretation of Dreams", establish psychoanalysis as Sigmund Freud's most significant contribution to human knowledge and, in a way, the intellectual hallmark of the 20th century. Freudian psychoanalysis, initially a therapeutic method for mental illness, subsequently expands into a general theory of the unconscious, a methodological tool for interpreting human relationships, and an ideology and worldview. It represents the discovery of a new scientific continent.