Know yourself and Ereignis: the inherent difficulties of the problem of the life as subject of the life - This paper aims to examine inherent difficulties of the possibility of human life to make itself subject of its own inquiry. By focusing on Plato’s warnings about the Delphic mandate “know yourself”, we will pointing out in what sense it could be a self-ignorance. Then, this self-ignorance will be interpreted from Martin Heidegger’s early considerations, to show how it derives from an objectifying tendency corresponding to the third person’s attitude. By taking the concept Er-eignis (appropriation) -used by the young Heidegger- as an indication, we will explore a possible way of considering the self apart from an accentuation of a reified I. Thus, it will propose to understand the Greek “know yourself” as an apprehension of the particular sense in which the own life unfolds according to its rhythm of appropriation of that, what it lives.