Most persons in talking of this subject say that they are sure of the reality of things when awake because their different senses concur in attesting it. They see a tree, and satisfy themselves that it is a tree by going up and touching it. They smell a rose, and go find the rose, look at it and handle it; while in dreams we are not able to apply these supplementary tests. The distinction is imaginary, for our senses likewise seem to support one another in dreams. We dream not only that we see an object, but also that we feel and hear it. When I dream of meeting a friend, I believe that I see him and shake hands with him and hear him speak. There is, therefore, a complete identity of the two conditions as to this point, and the thing that appears to me in a dream is a "bundle of sensations," visual, tactile, auditive, muscular, and often olfactory, just as it appears to me when awake. We are told of another difference. When awake, we find others agreeing with us in recognizing the reality of things. I see a tree, and so do those with me; I show it to them, and they look at it; I feel of it, and they touch it; I hear the rustling of the leaves, and so do they. Our perceptions in practical life are thus tested by comparison with those of others, whereas in our dreams we have our solitary and fanciful visions all within ourselves, with none to participate in our perceptions of them. This supposed contrast is no more real than the former one. What is true is that when we are once awake we change our point of view, and our vision of the night then seems to have been wholly interior, solitary, and subjective. But, notwithstanding the common illusion, _while we are dreaming_ affairs pass, to us, exactly as when we are awake. It is true that in the waking state we find ourselves mingled with other men, who perceive the same objects that we do. Do we not sometimes dream that we are one of an audience looking at a play? that we are talking with a friend, and exchange views with him? and that we understand one another perfectly? There is, therefore, in this aspect, not a difference but identity between the dream and the waking. The interior condition, the sensation, the credence, are identical. The dreaming man believes, sees, and feels himself in intercourse with his fellows, just as the man awake believes, sees, and feels it. When we wake, we discover our mistake, but what of that? It does not prevent us from believing completely in it while we are asleep. And this is the point; for, after all, am I sure that I shall not awake some day from what I now call my waking life? And who knows whether I shall not then judge that I have been dreaming a solitary dream? It may be added that the agreement of witnesses is not a decisive sign by which to distinguish the reality from the dream. There are collective hallucinations.