The purpose of what follows is to show that, in the 1775 collection of notes called the "Duisburg Nachlaß" (henceforth, DN), Kant adapted central ideas from his early metaphysics in order to clarify the role of the thinking subject as a necessary condition of empirical knowledge. I shall try to show how these adaptations were made, how they were philosophically significant, and how they can help us understand what Kant was trying to do in the mid-1770s. The DN was written up when some of his most far-reaching ideas were starting to take shape. If we could make sense of it, it might ultimately shed light on the way Kant arrived at the mature statement of his theoretical philosophy in the Critique of Pure Reason. I cannot reconstruct the whole of this story or even offer a complete account of the DN in this paper. But I do hope to point out and clarify one interesting fact. By the mid-1770s, the thinking subject had taken the place Kant had reserved for God in his earlier metaphysics. That some such displacement was important for Kant is not an especially new or even exciting thesis. However, as I shall argue, the philosophical interest of the thesis lies in seeing exactly how Kant effected the displacement. © Walter de Gruyter 2006.