From the rise of the “human sciences” in the 18th century, through the psy- sciences of the 20th century to the more recent neurosciences, the modern self emerged through a complex history of practices and concepts, under the gaze of medicine, psychiatry, physiology, psychoanalysis, etc. This history involves, on the one hand, the relationships between the self, the body and the brain, and, on the other, the position of the self as an object somehow in between political and scientific normativity. This paper tries to describe a methodological device for looking at how the self historically emerged as a concept, and at how it has been individuated and stabilized as an object through scientific practices. The argument proceeds in three steps. First, Daston and Galison’s historical epistemology of objectivity is discussed, highlighting some central methodological claims, but also pinpointing some critical points with respect to the history of the psy- sciences. Second, an historical example from late 19th century French psychiatry and its treatment of “sexual inversion” will support a systematic claim about how to understand both styles of reasoning and relations between concepts and practical techniques in the history of the sciences of the self. Third, two examples of the history of the sciences of the self will be used to mark a distinction between social history and historical epistemology.