By the preceding explanations of the processes in seeing and feeling, I have incontestably shown that empirical perception is essentially the work of _the Understanding_, for which the material only is supplied by the senses in sensation--and a poor material it is, on the whole; so that _the Understanding_ is, in fact, the artist, while the senses are but the under-workmen who hand it the materials. But the process consists throughout in referring from given effects to their causes, which by this process are enabled to present themselves as objects in Space. The very fact that we presuppose Causality in this process, proves precisely that this law must have been supplied by the Understanding itself; for it could never have found its way into the intellect from outside. It is indeed the first condition of all empirical perception; but this again is the form in which all external experience presents itself to us; how then can this law of Causality be derived from experience, when it is itself essentially presupposed by experience?--It was just because of the utter impossibility of this, and because Locke's philosophy had put an end to all _à priority_, that Hume denied the whole reality of the conception of Causality. He had besides already mentioned two false hypotheses in the seventh section of his "Inquiry concerning the Human Understanding," which recently have again been advanced: the one, that the effect of the will upon the members of our body; the other, that the resistance opposed to our pressure by outward objects, is the origin and prototype of the conception of Causality. Hume refutes both in his own way and according to his own order of ideas. I argue as follows. There is no causal connection whatever between acts of the will and actions of the body; on the contrary, both are immediately one and the same thing, only perceived in a double aspect--that is, on the one hand, in our self-consciousness, or inner sense, as acts of the will; on the other, simultaneously in exterior, spacial brain-perception, as actions of the body.[91] The second hypothesis is false, first because, as I have already shown at length, a mere sensation of touch does not yet give any objective perception whatever, let alone the conception of Causality, which never can arise from the feeling of an impeded muscular effort: besides impediments of this kind often occur without any external cause; secondly, because our pressing against an external object necessarily has a motive, and this already presupposes apprehension of that object, which again presupposes knowledge of Causality.--But the only means of radically proving the conception of Causality to be independent of all experience was by showing, as I have done, that the whole possibility of experience is conditioned by the conception of Causality. In § 23 I intend to show that Kant's proof, propounded with a similar intent, is false.