In thinking the question of responsibility between Levinas and Heidegger, it is both a movement of expropriation towards the other and a relation to a secret that come to the fore. Levinas' entire itinerary of thought has been structured by the effort to escape the closure of philosophies of totality, to exceed the horizon as such, to move beyond ontology, a movement towards exteriority or towards the other that has taken with it and redefined the very concept of responsibility. No longer a responsibility for oneself, or for one's actions, but a responsibility for the other and for the sake of the other. However, can the other only be said to lie beyond being, if being, as Heidegger would show, is itself the beyond, the transcendent pure and simple? Being might include a relation to the other, which explains why Heidegger thematizes being-with as a constitutive feature of existence. To that extent, one may seek to inquire into the ontological senses of responsibility. Heidegger's thought of being entails a profound philosophy of responsibility. But it is no longer developed in terms of subjectivity, even in its reversal. Rather, Heidegger shows that one is ultimately responsible for an inappropriable, a secret or mystery. This secret of being represents a sense of otherness that is not reduced, as in Levinas, to the "other human being," that is, within a subjectivist, anthropocentric horizon. I will explore in the following pages the terms of this debate.