All philosophers make the common mistake of taking contemporary man as their starting point and of trying, through an analysis of him, to[21] reach a conclusion. "Man" involuntarily presents himself to them as an aeterna veritas as a passive element in every hurly-burly, as a fixed standard of things. Yet everything uttered by the philosopher on the subject of man is, in the last resort, nothing more than a piece of testimony concerning man during a very limited period of time.