We will certainly take this source of error into consideration in all cases of telepathy and also of clairvoyance.

Benoit's supposition that delicacy of the sense of smell is of importance in thought-reading seems to me more than problematical. Wernicke, who is a very objective investigator, has expressed a similar view to Benoit's, but with all reserve. He thinks that concentration of the will, coupled with a cheery expectation that the experiment will succeed, or a depressing feeling that it will fail, may, so to speak, bring about a change in the atmosphere surrounding the hypnotizer and thereby act indirectly on the subject's extremely delicate sense of smell. Consequently, it might be possible for the subject to detect from some change in the sensation of smell the direction in which the experimenter's will is working, and to act accordingly. Wernicke therefore proposed that experiments should be made with experimenter and subject separated by a glass-plate so as to exclude the possibility of the sense of smell being affected.

I have discussed these sources of error in some detail, because their importance is so frequently underrated. At all events, let us firmly bear in mind that the possibility of recognized sense-impressions leading to the correct solution of a problem is far greater than superficial observation would lead us to imagine. Thus, some persons think that when the subject is blindfolded and is not in contact with the experimenter, supersensual thought-transference takes place, whereas, as I have just explained, there are numerous other sources of perception besides whispering. Consequently, it would be very rash to conclude that such experiments establish the existence of supersensual thought-transference, or that the latter in any way supports the theory of animal magnetism.

It is also on these grounds that I have already mentioned that Scheibler could not prove the existence of animal magnetism. Herr Scheibler pretended he could do so by means of thought-transference. The experiments were carried out as in ordinary thought-reading. Not only was Scheibler blindfolded, but he was also not allowed to touch the subject experimented on. Scheibler left the room, and it was arranged during his absence what he was to do - for example, to fetch a book from the table and put it on a chair. Scheibler was then brought in blindfolded, and his friend A. was told to think steadfastly of the allotted task. Scheibler did not touch A., but the latter's hand was quite close to him. As it turned out, Scheibler certainly did sometimes perform the task set him correctly, though, as a rule, only after some failures.

Carefully conducted controlling experiments showed that the successes were not due to any magnetic or unknown power. Directly Scheibler was made to wear gloves, and had his ears stopped as well as his eyes bandaged, the experiments failed. From this it follows, at all events, that the experiments did not prove successful when the recognized sense-impressions were excluded. I think it probable that auditory impressions were responsible for the successful cases. Any one who has the opportunity for making or seeing such experiments, and who at the same time carefully watches the spectators, will be astonished to find how distinct and loud the sounds sometimes are, that the uncritical occultists consider excluded.

I have here intentionally discussed but one source of error in telepathy; I shall come to the others later on. I will only further remark, that the exclusion of one source of error alone is never sufficient. On the contrary, all sources of error must be excluded if we are to arrive at an unimpeachable conclusion.

I now come to clairvoyance, which is the perception of things distant in time or space. In the former, forthcoming events are foretold, or past ones, about which the clairvoyant could have learned nothing by normal means, recounted; in the latter, things are seen which are so placed in space as to be invisible - i.e., they are either separated from the clairvoyant by some non-transparent substance, or they are too far off to be seen. The somnambulic state1 induced by magnetizing is said to favour clairvoyance. For a long time clairvoyant somnambulia was a special profession, and is so to the present in many towns. The belief in clairvoyance goes back as far as history; I need only refer to the Bible and the Greek Oracles. It seems that the state of the Pythia was like a hypnosis, although toxic methods were probably also used. Kluge, Ed. von Hartmann, and others, think that the state was somnambulia. It was the same thing with the Sibyl of Cumae. Other phenomena of antiquity must also be included here - for example, the reports of Apuleius about the prophesying of boys; as well as many phenomena reported in recent times from various countries.

Stecker tells us that in the camp of King John of Abyssinia, 1882, a boy in an apparently somnambulic condition was employed to discover a thief (cf. p. 3).

1 The magnetic states in which such phenomena as clairvoyance, thought-transference, etc., occur, are specially called somnambulia by mesmerists. Consequently the word somnambulia is used in several senses: t. One of Charcot's stages is often called somnambulia (cf. p. 81); 2. The Nancy school calls that state somnambulia in which there is loss of memory after waking; 3. Some identify hypnotism with somnambulia; 4. Somnambulia is a sleep in which there are actions and movements (p. 184); 5. The mesmeric state described above is called somnambulia*

When animal magnetism blossomed forth at the end of the eighteenth century, clairvoyance became more and more associated with it. It is not certain whether Mesmer himself believed in clairvoyance; but it would appear from one of his letters, published by Du Potet, that he did, but did not go deeply into the question. The numerous scientific commissions which have investigated clairvoyance have failed to establish the occurrence of the phenomena. Nevertheless, many people had a lasting belief in it, especially philosophers - Schopenhauer, for instance. Even Braid, about whose views there are so many mistaken opinions, believed in clairvoyance, at all events at first. There is a passage in his Neurypnology (p. 22), which I can interpret in no other way. Braid thought clairvoyance proved, though he had never seen it and could not induce it himself; but he thought that a number of those who vouched for its reality were scientific and truth-loving enough to be believed.