One more remark. Our formula contains, it will be observed, nothing to correspond to the great principle of cognition laid down by Professor Ferrier in his Institutes of Metaphysic and apparently adopted by all the followers of Fichte, the principle, namely, that for knowledge to be constituted there must be knowledge of the knowing mind along with whatever else is known: not q, as we have supposed, but q PLUS MYSELF, must be the least I can know. It is certain that the common sense of mankind never dreams of using any such principle when it tries to discriminate between conscious states that are knowledge and conscious states that are not. So that Ferrier's principle, if it have any relevancy at all, must have relevancy to the metaphysical possibility of consciousness at large, and not to the practically recognized constitution of cognitive consciousness. We may therefore pass it by without further notice here.] It is to be feared that the reader may consider this formula rather insignificant and obvious, and hardly worth the labor of so many pages, especially when he considers that the only cases to which it applies are percepts, and that the whole field of symbolic or conceptual thinking seems to elude its grasp. Where the reality is either a material thing or act, or a state of the critic's consciousness, I may both mirror it in my mind and operate upon it--in the latter case indirectly, of course--as soon as I perceive it. But there are many cognitions, universally allowed to be such, which neither mirror nor operate on their realities.