_Note._—As a warning against a false path and to illustrate the above, I mention S. Stern’s “_Vorläufige Grundlage zur Sprachphilosophie_,” 1835, which is an utterly abortive attempt to construct the categories out of the grammatical forms. He has entirely confused thought with perception, and therefore, instead of the categories of thought, he has tried to deduce the supposed categories of perception from the grammatical forms, and consequently has placed the grammatical forms in direct relation to perception. He is involved in the great error that _language_ is immediately related to _perception_, instead of being directly related only to thought as such, thus to the _abstract concepts_, and only by means of these to perception, to which they, however, have a relation which introduces an entire change of the form. What exists in perception, thus also the relations which proceed from time and space, certainly becomes an object of thought; thus there must also be forms of speech to express it, yet always merely in the abstract, as concepts. Concepts are always the primary material of thought, and the forms of logic are always related to these, never _directly_ to perception. Perception always determines only the material, never the formal truth of the proposition, for the formal truth is determined according to the logical rules alone. ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ I return to the Kantian philosophy, and come now to the _Transcendental Dialectic_. Kant opens it with the explanation of _reason_, the faculty which is to play the principal part in it, for hitherto only sensibility and understanding were on the scene. When considering his different explanations of reason, I have already spoken above of the explanation he gives here that “it is the faculty of principles.” It is now taught here that all the _a priori_ knowledge hitherto considered, which makes pure mathematics and pure natural science possible, affords only _rules_, and no _principles_; because it proceeds from perceptions and forms of knowledge, and not from mere conceptions, which is demanded if it is to be called a principle. Such a principle must accordingly be knowledge _from pure conceptions_ and yet _synthetical_. But this is absolutely impossible. From pure conceptions nothing but _analytical_ propositions can ever proceed. If conceptions are to be synthetically and yet _a priori_ combined, this combination must necessarily be accomplished by some third thing, through a pure perception of the formal possibility of experience, just as synthetic judgments _a posteriori_ are brought about through empirical perception; consequently a synthetic proposition _a priori_ can never proceed from pure conceptions. In general, however, we are _a priori_ conscious of nothing more than the principle of sufficient reason in its different forms, and therefore no other synthetic judgments _a priori_ are possible than those which proceed from that which receives