But there is a difference between dreams and waking life, which is of far too great importance for any of us to be in danger of neglecting it. When I see a man in my dream, there is just as good a body as if I were awake; muscles, nerves, circulation, capability of adapting means to ends. If only the dream is coherent enough, no physical test can establish that it is a dream. In both cases I see and feel the same thing. In both cases I assume the existence of more than I can see and feel, namely, the consciousness of this other man. But now here is a great difference, and the only difference--in a dream this assumption is wrong; in waking life it is right. The man I see in my dream is a mere machine, a bundle of phenomena with no underlying reality; there is no consciousness involved except my consciousness, no feeling in the case except my feelings. The man I see in waking life is more than a bundle of phenomena; his body and its actions are phenomena, but these phenomena are merely the symbols and representatives in my mind of a reality which is outside my mind, namely, the consciousness of the man himself which is represented by the working of his brain, and the simpler quasi-mental facts, not woven into his consciousness, which are represented by the working of the rest of his body. What makes life not to be a dream is the existence of those facts which we arrive at by our second process of inference; the consciousness of men and the higher animals, the sub-consciousness of lower organisms and the quasi-mental facts which go along with the motions of inanimate matter. In a book which is very largely and deservedly known by heart, 'Through the Looking-glass,' there is a very instructive discussion upon this point. Alice has been taken to see the Red King as he lies snoring; and Tweedledee asks, 'Do you know what he is dreaming about?' 'Nobody can guess that,' replies Alice. 'Why, about you,' he says triumphantly. 'And if he stopped dreaming about you, where do you suppose you'd be?' 'Where I am now of course,' said Alice. 'Not you,' said Tweedledee, 'you'd be nowhere. You are only a sort of thing in his dream.' 'If that there King was to wake,' added Tweedledum, 'you'd go out, bang! just like a candle.' Alice was quite right in regarding these remarks as unphilosophical. The fact that she could see, think, and feel was proof positive that she was not a sort of thing in anybody's dream. This is the meaning of that saying, Cogito ergo sum, of Descartes. By him, and by Spinoza after him, the verb cogito and the substantive cogitatio were used to denote consciousness in general, any kind of feeling, even what we now call sub-consciousness. The saying means that feeling exists in and for itself, not as a quality or modification or state or manifestation of anything else.