We have here a hypnotized subject to whom I say that when he wakes he is to take a flower-pot from the window-sill, wrap it in a cloth, put it on the sofa, and bow to it three times. All of which he does. When asked for his reasons he answers, "You know, when I woke and saw the flower-pot there I thought that as it was rather cold the flower-pot had better be warmed a little, or else the plant would die. So I wrapped it in the cloth, and then I thought that as the sofa was near the fire I would put the flower-pot on it; and I bowed because I was pleased with myself for having such a bright idea." He added that he did not consider the action foolish, he had told me his reasons for so acting.

In this case the subject carried out an absurd post-hypnotic suggestion; he was unconscious of the constraint put upon him, and tried to find good reasons for his act. Most experimenters have observed that their subjects try to find reasons for having carried out even the most foolish acts suggested. This mental process so frequently follows the execution of a post-hypnotic suggestion that some experimenters have come to look upon it as the rule - but such an assumption is undoubtedly erroneous.

We thus see that when subjects are questioned as to their motive they make different answers; they either believe that they have so acted of their own accord, and invent reasons for their proceedings, or they say they felt impelled to act so; or they only say, "It came into my head to do it." We can use suggestion here also. When the original suggestion is being made, it may, at the same time, be suggested to the subject to believe that he has acted of his own free-will (Forel), or to believe that constraint was put upon him. When such a suggestion is not made, it depends upon the subjects power of self-observation which reason he gives - whether he perceives the restraint, or invents false reasons for his conduct. Something also depends upon the frequency with which the experiment is made, and particularly on the greater or lesser absurdity of the suggested act. This endeavour of certain subjects to find a motive for their apparently free acts is very instructive, and has, as we shall see, a certain value in determining our conception of free-will from a psychological and philosophical point of view.

Post-hypnotic suggestions are of especial value for the induction or prevention of future hypnosis. In this way an easily hypnotizable person may be prevented from allowing himself to be hypnotized by another subject. Post-hypnotic suggestion is an excellent means for protecting susceptible * people and guarding them against unexpected hypnosis, as Ricard pointed out for the somnambulic state. Mr. X., whom I had often hypnotized, had also often been hypnotized by Mr. A. I suggested to X. that he should in future only allow himself to be hypnotized by doctors, but on no account by Mr. A. After this Mr. A. could no longer hypnotize him. However, I do not believe that this is a perfect protection in all cases. But the chief danger, which does not arise from susceptibility to hypnotism, but from susceptibility to hypnotism against the subject's will, is thereby guarded against. On the other hand, it is possible to throw a subject into an unexpected hypnosis by means of post-hypnotic suggestion. I say to a subject, "Directly I say the word 'to-day' you will fall into a fresh hypnosis." I then wake him, and he remains awake until I say "to-day"; upon which he is instantly thrown into a fresh hypnosis.

It is difficult to say for what length of time the carrying out of a post-hypnotic suggestion may be successfully deferred, since this depends on the subject's character and the method employed. The longest post-hypnotic suggestion I have seen was executed at the end of four months; no hint had been given to the subject in the meantime. The longest which has ever been described, as far as I know, was in a subject under Liegeois and Liebeault; in this case exactly a year elapsed before the suggestion was carried out. The case of the photograph, mentioned on page 161, in which the photograph remained visible for two years is rather different, as it appears that the suggestion was often recalled to the subject's memory. The case mentioned by Dal Pozzo is, perhaps, of the same kind: a person who was afraid of thunderstorms was cured of the fear by post-hypnotic suggestion. The effect is said to have lasted twenty-six years (Belfiore).

I have hitherto only discussed those post-hypnotic suggestions in which there is loss of memory after waking from hypnosis. This loss of memory greatly favours the carrying out of the suggestion; but it is not a necessary condition, for post-hypnotic suggestions are often executed in spite of the memory remaining intact. These cases are highly interesting, because the compulsion can be better observed in them. The subject knows that his action was the result of a hypnotic suggestion from which he could not escape. Sometimes suggestion only succeeds with difficulty and after a long struggle, in consequence of the subject's resistance and control of his consciousness.

One of my colleagues, a doctor, was in the post-hypnotic state; I suggested abnormal movements to him with success; sense-delusions did not succeed. I told him that after he woke he would be unable to say his name whenever I laid my hand on his forehead, and further that instead of his own name he should always say mine. When he woke from the hypnosis, whenever I put my hand on his forehead he said his name was Moll; he knew his right name also, but was unable to say it. He remembered my order about it, and did not believe in any supernatural force; he knew that the effect was mental, but could not help himself.

It is the same thing with sense-delusions, they can also be produced post-hypnotically, in spite of the fact that the suggestion is remembered. It is true that the effect of the sense-delusion in such cases is often not to be seen, because, as the order is remembered, reasoning is possible, and thus the suggestion is negatived. Nevertheless, sense-delusions with remembrance of the suggestion are rarer, because loss of memory more frequently follows hypnosis with sense-delusions, even though the loss of memory can always be prevented by post-hypnotic suggestion.