I was once reading inattentively, seated at my ease in a lounging chair, and my thoughts took quite another direction, wandering vaguely from one thing to another.  All at once some people entered an adjoining room talking together; I heard what they said indistinctly, but the word Florence reached my ears, and I soon imagined myself to be in that city, and going on from one association to another I continued for some time to see again the places, monuments, and people I had known there.  Yet I was fully awake, and from time to time I brushed the flies from my face and glanced at the clock on the chimney-piece, since I had to go out at three o’clock.

It appears from this fact, which will be confirmed by many of my readers, that some waking states resemble those of dreams in form, and moreover they are sometimes even alike in substance.  Ideas and thoughts in the conditions just indicated may not only be latent, active, combined, or transformed by suggestive impulses, but ideas are represented by images in such vivid relief that, until the observer recollects himself, they are seen and felt by him with the same sense of reality as in a dream.  This mental transformation is however so habitual, that the implicit conviction of being really awake, does not allow us to observe what the actual nature of the phenomenon is, since there is an immediate transition from an implicit perception of the image as real to the habitual form of simple thought, without distinguishing the difference between these two states of consciousness.  Any one who has long practised himself in the observation of such distinctions will, however, be able to understand the psychical process and to estimate its value.

It has often occurred to myself, in circumstances analogous to the above, when thinking of persons or places at a distance, to see them imaged before me in such vivid relief that I have been startled as if by a morbid hallucination.  Once, in passing through my chamber, my attention was so strongly fixed on an absent person that I was not only vividly conscious of his form, but also of his voice and gestures, so that I was amazed by the lively image brought before me.  I could adduce other instances from my own experience and that of others to show that in a waking and altogether normal state we may believe in the reality of the image as we do in dreams.

This vivid and momentary realization of images is very common in the lower classes, who often talk to themselves, and use gestures which show that they are conversing at the moment with imaginary persons, who stand before them, as if they were really there, in the same manner as in dreams.  Indeed, every one has experienced this phenomenon for himself, especially when strongly excited by anger, sorrow, or hope.  If it were possible to reflect on the process of thought at the time we should distinctly understand that we were dreaming while still awake.