" This heart within me I can feel, and I judge that it exists. This world I can touch, and I likewise judge that it exists. There ends all my knowledge, and the rest is construction. For if I try to seize this self of which I feel sure, if I try to define and to summarize it, it is nothing but water slipping through my fingers. I can sketch one by one all the aspects it is able to assume, all those likewise that have been attributed to it, this up bringing, this origin, this ardor or these silences, this nobility or this vileness. But aspects cannot be added up. This very heart which is mine will forever remain indefinable to me. Between the certainty I have of my existence and the content I try to give to that assurance, the gap will never be filled. Forever I shall be a stranger to myself. In psychology as in logic, there are truths but no truth. Socrates' " Know thyself" has as much value as the " Be virtuous" of our confessionals. They reveal a nostalgia at the same time as an ignorance. They are sterile exercises on great subjects. They are legitimate only in precisely so far as they are approximate. "