he must indeed have thought =beneath= all criticism. Meanwhile, a certain imperious and oracular Reason of the same kind is still, at the Universities, fastened on the shoulders of our innocent youth. NOTE. If we wish to reach the real origin of this hypothesis of Practical Reason, we must trace its descent a little further back. We shall find that it is derived from a doctrine, which Kant totally confuted, but which nevertheless, in this connection, lies secretly (indeed he himself is not aware of it) at the root of his assumption of a Practical Reason with its Imperatives and its Autonomy--a reminiscence of a former mode of thought. I mean the so-called Rational Psychology, according to which man is composed of two entirely heterogeneous substances--the material body, and the immaterial soul. Plato was the first to formulate this dogma, and he endeavoured to prove it as an objective truth. But it was Descartes who, by working it out with scientific exactness, perfectly developed and completed it. And this is just what brought its fallacy to light, as demonstrated by Spinoza, Locke, and Kant successively. It was demonstrated by Spinoza; because his philosophy consists chiefly in the refutation of his master's twofold dualism, and because he entirely and expressly denied the two Substances of Descartes, and took as his main principle the following proposition: "_Substantia cogitans et substantia externa una eademque est substantia, quae jam sub hoc, jam sub illo attribute comprehenditur._"[19] It was demonstrated by Locke; for he combated the theory of innate ideas, derived all knowledge from the sensuous, and taught that it is not impossible that Matter should think. And lastly, it was demonstrated by Kant, in his _Kritik der Rationalen Psychologie_, as given in the first edition. Leibnitz and Wolff were the champions on the bad side; and this brought Leibnitz the undeserved honour of being compared to the great Plato, who was really so unlike him.