Moreover, we find that something similar happens in the case of animals. Indeed, it is mainly on this that the training of animals is based. Smugglers train their dogs to avoid frontier-guards by having them constantly beaten and otherwise maltreated by men wearing the uniform of such officials. The consequence is that the dogs run away directly they see a man in the uniform of a frontier-guard approaching. Loiset describes a trick-act which used often to be given in circuses - the little hump-backed tailor who tries to mount a horse but cannot, because it always lashes out at him, and bites and chases him as would a rabid dog. The horse chosen for this spectacle was one that had been teazed from a foal, more especially by a supposed tailor clad in a quaint costume, who maltreated it in various ways. Consequently, whenever any one similarly clad approached it, the horse lashed out, etc., but was quiet and obedient to persons in ordinary dress. There is no reason to suppose that an animal, any more than a man, recollects all the details of former injury because of the costume of its torturer. Much has been said in this connection of the sagacity of animals, but such remarks are merely the outcome of superficial observation.

In reality, these are but mechanical associations in which, as in the case of the horse and the tailor where the sight of the latter in his quaint costume caused the former to bite and kick, one process calls up the other corresponding process without there being any recollection of the earlier experiences from which this linking together resulted.

In short, we have no occasion to consider it particularly enigmatical that the original command in post-hypnotic suggestion is forgotten, and that only the idea of carrying out the command rises to the primary consciousness. The process is here exactly the same as in the cases just mentioned. It is the idea of what is to happen, and not the source from which that idea springs, that is remembered, and this, as we have just seen, is a process which has its analogies in many cases which are outside the domain of hypnosis.

I have hitherto spoken only of post-hypnotic movements and actions, and have endeavoured to explain the most important phenomena by means of analogy. I have still a few words to say about post-hypnotic sense-delusions, which are less easy to explain. It is true that those which occur in a fresh hypnosis hardly present any substantial difficulty. We have seen that the subsequent loss of memory is only apparent, and that the idea really remains in the secondary consciousness. Consequently, it is not surprising that the suggested idea should at an appointed time transform itself into a sense-delusion in a fresh hypnosis, which hypnosis comes on through association when the idea reappears. We must then explain the sense-delusion by means of the dream-consciousness as I have shown above.

It is quite another thing when the sense-delusion appears without a new hypnosis. For example, I say to some one in hypnosis, "When I cough after you wake, you will see a pigeon sitting on the table; you will remain thoroughly awake." The suggestion takes effect; the subject sees a pigeon where no pigeon is. But it is impossible to make him accept a further suggestion; that one point excepted, he seems perfectly normal. Whether the total mental state of such people is really normal, is a question on which Bentivegni speaks very clearly, and will be discussed in the legal section of this book. Now, how can we explain this particular sense-delusion ? Dream-consciousness does not afford a satisfactory explanation, although Eduard von Hartmann believes that it always co-exists with waking consciousness. But even if we admit this it brings us no nearer a solution, for we should still have to explain how it happens that dream-consciousness is only manifest in respect to one point, waking consciousness being present in all others. But even if the dream-consciousness does not provide a satisfactory explanation we find like occurrences under different circumstances.

I do not mention the hallucinations of insane persons, because it is exactly the addition of other disorders to their sense-delusions which distinguishes them from the above case. But we find isolated sense-delusions in persons who for some reason or other "are disinclined to correct the creations of their own imagination." Krafft-Ebing mentions the delusions of several famous men - the case of Socrates, who conversed with his Daemon, and Luther, who threw an inkstand at the devil. Statistical investigations on hallucinations among normal persons have lately been carried out by the English Society for Psychical Research. These results were presented by Sidgwick at the Congress for Experimental Psychology in London, in 1892, and they were discussed in detail by Parish in his work Ueber die Trugwahrnehmungen (Hallucinations and Illusions). Parish holds that sense-delusions in themselves are no indication of disease, but that usually when they are present an abnormal psychic state may be demonstrated. Such delusions are often caused by strong expectant attention, of which I have already spoken.

This is very clearly seen in spiritualistic manifestations, which may be ascribed in great part to hallucinations of the spectators, who think they see spirits or other things in consequence of abnormal processes in their own brain. The visions of religious enthusiasts, which sometimes take an epidemic form, belong here. In these latter cases the sense-delusions result from a particular mental state which may be called a state of expectation. It thus appears that the induction of sense-delusions by means of post-hypnotic suggestion brings about a mental state when the idea reappears, which, although the subject is otherwise awake, has a great resemblance to this state of expectation, and is perhaps even identical with it.

Again, too much weight should not be laid on solitary cases of post-hypnotic sense-delusion, as it is always very rare for the subject to remain quite awake and unable to accept fresh suggestions. As we have already seen, a fresh state of susceptibility to suggestion, which we can only ascribe to hypnosis, readily sets in even while post-hypnotic actions are being carried out. At all events, in these cases of post-hypnotic suggestion the more absurd the latter is and the more opposed to the subject's natural disposition, the more readily does a fresh hypnosis arise. We can explain this process as the result of associations which create a state of dream-consciousness when the process in question does not harmonize with a state of waking consciousness.