What is not permissible is to declare that sensation is a psychological phenomenon, and to oppose this phenomenon to physical reality, as if this latter could be known to us by any other method than sensation. If the opinion I uphold be accepted, if we agree to see in sensation, understood in a certain way, a physical state, it will be easy to extend this interpretation to a whole series of different phenomena. To the images, first, which proceed from sensations, since they are recurring sensations; to the emotions also, which, according to recent theories, result from the perception of the movements which are produced in the heart, the vessels, and the muscles; and finally, to effort, whether of will or of attention, which is constituted by the muscular sensations perceived, and consequently also results from corporeal states. The consequences must be clearly remarked. To admit that sensation is a physical state, is to admit, by that very fact, that the image, idea, emotion, and effort--all those manifestations generally ascribed to the mind alone--are also physical states. What, then, is the mind? And what share remains to it in all these phenomena, from which it seems we are endeavouring to oust it? The mind is in that special activity which is engaged in sensation, image, idea, emotion, and effort. For a sensation to be produced; there must be, as I said a little time ago, two elements: the something felt--a tree, a house, an animal, a titillation, an odour,--and also the fact of feeling this something, the consciousness of it, the judgment passed on it, the reasoning applied to it--in other terms, the categories which comprehend it. From this point of view, the dualism contained in sensation is clearly expressed. Sensation as a thing felt, that is, the physical part, or matter; sensation as the fact of feeling or of judging, that is, the mind. Mark the language I use. We say that matter is the something felt; but we do not say for the sake of symmetry, that the mind is the something which feels. I have used a more cautious, and, I think, a more just formula, which places the mind in the fact of feeling. Let me repeat again, at the risk of appearing too subtle: the mind is the act of consciousness; it is not a subject which has consciousness. For a subject, let it be noted, a subject which feels, is an object of cognition--it forms part of the other group of elements, the group of sensations. In practice we represent by mind a fragment of our own biography, and by dint of pains we attribute to this fragment the faculty of having a consciousness; we make it the subject of the relation subject-object. But this fragment, being constituted of memories and sensations, does not exactly represent the mind, and does not correspond to our definition; it would rather represent the mind sensationalised or materialised.