ABSTRACT: The discussion of Heidegger's destructive retrieve of Aristotle has been intensified in recent years by the publication of Heidegger's courses in the years surrounding his magnum opus. Heidegger's explicit commentary on Aristotle in these courses permits one to read Being and Time with Aristotle's Nicomachean Ethics and Metaphysics. My paper analyzes a network of differences between the two thinkers, focusing on the relationship between theory and praxis. From Aristotle to Heidegger, there is: (1) a shift from the priority of actuality to the priority of possibility. This shift, I argue, is itself the metaphysical ground of: (2) a shift from the priority of theory to the priority of praxis. This shift is seen most clearly in the way in which (3) Heidegger's notion of Theorie is a modification of his poesis. The temporal ground of the reversal is seen in (4) Heidegger's notion of transcendence towards the world, and not towards an eternal being.