In a 1941 lecture, Pierre Thévenaz (1913-1955) examines the question “Who am I?” using the reflexive method of analysis. In a bottom-up approach, the philosopher starts from a purely biological and external answer and, after the psychological and ethical stages, arrives at the philosophical or metaphysical solution: through the Cartesian cogito, the ego correlates thought and being. This being must be understood as activity: the “I” then has the internal experience of acting freely, as a cause of itself. The “being” of the self is pure becoming, and therefore pure spirituality. Non-being is thus also defined as spirituality: it is the non-presence of the mind to itself.