 Although overcoming the distinction between thought and being by relying on self-relating activities might be seen as a common goal of all the major German idealistic thinkers, they pursued this project in very different directions. The first post-Kantian philosopher who embarked explicitly on the project to elaborate a dynamic idealistic conception of reality that was based on what he took to be conditions of knowledge/cognition and agency and that was built on a specific conception of self-consciousness was Johann Gottlieb Fichte (1762–1814) while he was a professor at the university of Saxe-Weimar in Jena from 1794 to 1799. In his Doctrine of Science (1794/95) and in the First and Second Introduction into the Doctrine of Science (1797) he famously set out to demonstrate that the primordial act of self-positing lies at the basis of all reality as far as it is an object of knowledge/cognition and agency. His starting-point is an epistemological question: how does it come that we cannot help but experience objective reality the way we do, i.e., in terms of spatio-temporal objects standing in determinate relations? Where do these representations of objects, of relations and especially the belief that they exist come from? And (most importantly): how can we have knowledge of objective reality that is not subject to skeptical doubts? In order to answer these questions Fichte pursues at different times different strategies. The best known and most influential of these attempts is documented in the first published version of his Doctrine of Science. In what follows we will focus primarily on the line of thought presented in this text, although Fichte changed his arguments considerably in the First and Second Introductions into the Doctrine of Science.