While the present work analyzes three distinct motifs? body, world, with? in the work of Jean-Luc Nancy, the dissertation intends to investigate Nancy?s reading of Heidegger, with particular focus on the question of Being-with. Given the nature of the reflection? opening the question of otherness from within Heidegger? the research will also articulate a dialogue between Nancy and Levinas. Through the examination of Nancy?s reading of Heidegger, the dissertation will then endeavor to establish the original gesture of Nancy?s contribution to philosophy, which will be identified in the concept of powers of existence. Under the light of the analysis of the three concepts which structure the work, the conclusions will define powers of existence as singular resistances of existence to the mastering decision of philosophical work. This being the case philosophy will in turn continuously loosen its categories and key words in the attempt to decide its course according to what happens between us. The opening of a series of incommensurable measures responds to the demand existence casts on philosophical work. The problem of otherness is thus resolved as the work of powers of existence.