In 1954, the French translation of Traum und Existenz by the Swiss psychologist and psychiatrist Ludwig Binswanger was published, accompanied by an introduction by Michel Foucault. In these pages the philosopher announced the project of a "twisting of phenomenology towards anthropology" to analyze "what were the foundations offered to concrete reflection on man". Foucault never published the book, but kept the manuscript presented here. In these pages he carried out a systematic examination of Daseinsanalyse, comparing it with the approaches of psychiatry, psychoanalysis and phenomenology, and praising its ambition to understand mental illness. This approach accompanied him in his search for "something different from the traditional grids of the psychiatric gaze", a "counterweight"; however, the French philosopher had already highlighted its ambiguities and weaknesses, in particular a drift towards metaphysical speculation which distanced him from "concrete man". We are witnessing, in fact, a double abandonment: first of psychiatry and then of existential analysis itself, which will soon lead to the radically new perspective of the History of Madness in the Classical Age. The sign of this work, however, would not disappear. In fact, in 1984 Michel Foucault presented his History of Sexuality in the following terms: “Studying the forms of experience in this way, in their history, is a theme that came to me from an older project: that of using the methods of existential analysis in the field of psychiatry and mental illness".