 Granted, then, that a system of philosophy must begin with a single, immediately certain, synthetic first proposition or “grounding principle”: where might one turn in order to discover and to recognize the first principle in question, a proposition that alone can serve as the foundation or “ground” of all other philosophical propositions and cannot itself be established by any argument? The answer is, we must turn within—to the consideration of consciousness itself. This, Reinhold maintained, is precisely what Kant (not to mention Descartes) had done, albeit he did not succeed in presenting the fruits of his inquiries in an adequately scientific and systematic form.