But, again, this testimony depends on the utilisation of people endowed with exceptional faculties ; and these faculties are oc casionally imitated by those who do not really possess them— a procedure which must be stigmatized in the strongest terms as fraudulent. There are others who, while possessing the faculties in a small degree, are tempted to enlarge and extend the results by normal supplement : a tendency which has to be constantly guarded against, for, if unchecked, it tends to bring the whole subject into disrepute.
Meanwhile, however, a body of careful investigators, notably those who founded in London the Society for Psychical Research, and others who have joined them or formed similar Societies, have accumulated a great mass of evidence in favour of the phenomena; and the enquiry is still proceeding.
Assuming, on the strength of the evidence, that human faculties are not so limited as was at one time thought, and that these obscure phenomena actually occur, they may be classified into two great groups :—(i) the mental, or purely psychical branch, concerned with the reception of ideas and information,—informa tion which could not have been normally acquired by the operator and therefore has to be styled supernormal ; and (2) the physical branch, which concerns the production of effects in ordinary matter by apparently a supernormal extension of physiological processes.
To the first group belong such subjects as may be summarized under the heads telepathy, clairvoyance (qq.v.), lucidity, trance utterance, automatic writing, premonition, xenoglossy, psychom etry, and other apparent extensions of receptive faculty occa sionally summarized under the rather question-begging term of "cryptesthesia." It is chiefly on the strength of these mental phenomena that the hypothesis about the continued activity of the discarnate has grown up. For most of the communications so received purport to come, and certainly have the superficial appearance of coming, from intelligences no longer in the flesh, who desire to send messages of condolence, sympathy, and assurance to surviving relatives, and to furnish proof of their continued activity. To this group must also probably be added the visual and auditory hallucinations (if that term can be prop erly used) which many people have experienced in the form of apparitions, or other apparently sensory manifestations, of the people concerned. It has been found that these appearances, or voices, are not limited to those of dead people, as they can be traced sometimes to the unconscious influence of living people, when they are either asleep, or in some danger, or subject to some strong emotion. And these are called phantasms of the living.
The discovery of telepathy, that is to say the transference of thought or of ideas or emotions from one person to another without the use of any of the normal means of communication--a power which has been established by direct experiment as pos sessed by some people—tends to throw light upon these appari tions, and indeed upon the whole spiritistic hypothesis. For if it is possible for one mind to influence another without the use of the material mechanism commonly employed, it tends to dem onstrate an independence between mind and body which cannot fail to have important implications. Though neither the vocal cords nor any other muscles are used for transmission ; although neither the eye nor the ear, nor any of the other senses, are used for reception; yet, since some brain process must at least in directly be involved, it is just possible that telepathy may be due to some unknown method of transmission between brain and brain. But no evidence has ever been adduced, at least none of any trustworthy character, for the existence of what have been called "brain waves." And many circumstances connected with telepathy seem to render it unlikely that a physical method of transmission, even of an etheric kind, could be utilised for the purpose of transmitting information, even though something analogous to brain waves existed. The great distance over which thought-transference occurs, and its apparent independence of obstacles are against such a hypothesis. For although the analogy of wireless telegraphy is often adduced, it must be remembered that we have no means of apprehending etheric waves except by the use of definite instruments (a) for producing such waves in conscious and prearranged manner at one end, and (b) of detect ing and transmuting them into sound or other mechanical move ments at the other. Telepathy occurs without such instruments (assuming that it occurs at all), and nothing that has been de tected in a screened organ like the brain makes it able to act as either a receiving or a transmitting instrument except through the agency of the nerves and muscles. Consequently the most natural hypothesis is that telepathy is a purely mental phenomenon, an action of mind on mind apart from the bodily organs ; though the ultimate realization and demonstration of the occurrence must of course depend on the normal methods of testimony and record.