In the second place, when one examines closely the explanation materialism has imagined in order to derive thought from an action of matter, it is seen that this representation is rendered completely impossible by all we know of the nature of thought. For the materialist to suppose for one moment that thought is a cerebral function, he must evidently make an illusion for himself as to what thought is, and must juggle with concepts. Perhaps, could we penetrate into his own inmost thought, we should discover that at the moment he supposes a mere cell can manufacture the phenomena of consciousness, some vague image suggests itself to him whereby he identifies these phenomena with a light and subtle principle escaping from the nerve cell, something which resembles an electric _effluve_, or a will-of-the-wisp, or the flame from a punch-bowl.[46] I cannot, of course, tell whether my supposition is correct. But what I assert, with the calmness of perfect certitude, is that the materialist has not taken the pains to analyse attentively what he calls the phenomenon of consciousness. Had he made this analysis and kept the elements in his mind, he would have seen that it is almost impossible to hook in any way a phenomenon of consciousness on to a material molecule. In fact, also, to take this into account, we will not remain within the vagueness of the concept, but will take a particular example to argue upon, viz. that of an external perception. I open my window on a fine day, and I see before me a sunny plain, with, as far as the eye can reach, houses amongst the trees, and again more houses, the most distant of which are outlined against my far-off horizon. This is my mental phenomenon. And while I am at my window, my eyes fixed on the view, the anatomist declares that, starting from my retina, molecular vibrations travel along the optic nerve, cross each other at the chiasma, enter into the fascia, pass through the internal capsule and reach the hemispheres, or rather the occipital regions, of the brain, where, for the moment, we agree to localise the centre of projection of the visual sensations. This is my physical phenomenon. It now becomes the question of passing from this physical phenomena to the mental one. And here we are stopped by a really formidable difficulty. My mental phenomenon is not entirely mental, as is usually supposed from the deceitful brevity of the phrase. It is in great part physical, for it can be decomposed into two elements, a consciousness and its object; and this object of the consciousness, this group of little houses I see in the plain, belongs to sensation--that is to say, to something physical--or, in other words, to matter.