Only to a few people there comes occasionally in dreams a dim realisation of the unreality of the experience: 'After all, it does not matter,' they are able to say to themselves with more or less conviction, 'this is only a dream.' Thus one lady, dreaming that she is trying to kill three large snakes by stamping on them, wonders, while still dreaming, what it signifies to dream of snakes,[48] and another lady, when she dreams that she is in any unpleasant position--about to be shot, for instance--often says to herself: 'Never mind, I shall wake before it happens.' I have never detected in my own dreams any recognition that they are dreams. I may say, indeed, that I do not consider that such a thing is really possible, though it has been borne witness to by many philosophers and others from Aristotle and Synesius and Gassendi onwards. The phenomenon occurs; the person who says to himself that he is dreaming believes that he is still dreaming, but one may be permitted to doubt that he is. It seems far more probable that he has for a moment, without realising it, emerged at the waking surface of consciousness.[49] The only approach to a recognition of dreaming as dreaming that I have experienced, is connected with the reduplication that may sometimes occur, and the sense of a fatalistic predetermination. Thus I dreamed (with nothing that could suggest the dream) that I was one of a group of people who, as I realised, were carrying out a drama in which by force of circumstance I was destined to be the villain, having, by bad treatment, been driven to revenge. I knew at the outset how events would turn out, and yet, though it seemed real life, I felt vaguely that it was all a play that was merely being rehearsed. I had attained in the world of dreams to the Shakespearian feeling that it was all a stage, and I merely a player. So we may become the Prosperos of the life of dreams.[50] This quality of dreaming consciousness is a manifestation, and the chief one, of what is called _dissociation_.[51] In dissociation we have a phenomenon which runs through the whole of the dreaming life, and is scarcely less fundamental than the process of fusion by which the imagery is built up. The fact that the reasoning of dreams is usually bad, is due partly to the absence of memory elements that would be present to waking consciousness, and partly to the absence of sensory elements to check the false reasoning which, without them, appears to us conclusive. That is to say, that there is a process of dissociation by which ordinary channels of association are temporarily blocked, perhaps by exhaustion of their conductive elements, and the conditions are prepared for the formation of the hallucination. It is, as Parish has argued, in sleep and in those sleep-resembling states called hypnagogic that a condition of dissociation leading to hallucination is most apt to occur.[52]