It seems obvious enough that, from the moment when man first constituted himself as a positive figure in the field of knowledge, the old privilege of reﬂexive knowledge, of thought thinking itself, could not but disappear; but that it became possible, by this very fact, for an objective form of thought to investigate man in his entirety at the risk of discovering what could never be reached by his reﬂection or even by his consciousness: dim mechanisms, faceless determinations, a whole landscape of shadow that has been termed, directly or indirectly, the unconscious.