The topic receives its significance from the fact that suggestion is by far the most notable of the phenomena seen in hypnotism, also that its investigation is necessary to any kind of theoretical explanation. So many of the superstitions associated with abnormal psychic phenomena and long fostered under a respectable guise by various "Societies for Psychical Research," have been cleared away in late years, that we are at last in a position to investigate them along scientific lines. In order to do this, we must exclude any attempt at explanation based on the unknown or occult, and with the safeguard of scientific incredulity, proceed on the basis of the meagre but demonstrated facts at our disposal. The term "suggestion" means more than anything else, the clearing away of a long list of mysterious influences, and even to-day some of the old associations are attached to the word as may readily be seen from the book by Schmidkung and, perhaps in lesser degree, that of Sidis. But using the term in its entirely legitimate sense, however useful it may be in covering a certain group of facts, as attested by the excellent work of Bern-heim, still it has for the psychologist little or no meaning.

Only in proportion to a proper understanding of the facts upon which suggestion as a process rests, does it attain psychological value. These facts may be covered by the general term suggestibility, and it is our purpose to give a brief sketch of them on the basis of our present knowledge.

Theories attempting an explanation of the processes have been offered by various writers. As chief among those who attempt a purely physiological explanation may be mentioned Forel and Lehmann. The former of these * regards the mental life as having at its foundation a combination of separable brain forces, one of which corresponds to consciousness. For him suggestibility means the ability to break up the normal inter-connections of these forces, and the formation of new, at the instigation-of the suggesting agent. In opposition to this theory we may urge (1) that the only connections we know are those between psychical elements, that is, ideas, and (2) that such an appeal to suppositious brain forces, about which the physiologist knows nothing, is a clear violation of scientific method.

* Der Hypnotismus.

Lehmann proceeds from the partially known facts regarding the vasomotor control of blood in the brain, and makes suggestibility depend upon the variable supply in the different brain centers. His difficulty is that he makes what may possibly be regarded as a parallel physiological process the sole cause of the condition.

The only purely psychological theory, so far as I am aware, is that of Pierre Janet1 and Max Dessoir,2 incorporated by Moll in his, in many respects very same book, 3 the theory of the so-called "double consciousness." According to this view, there are two forms of consciousness, an "over" and an "under" consciousness, in the normal mind. The existence of the "under" consciousness is supposed to be proved by such facts as the sudden coming in of a name which We have tried in vain to recall, dream consciousness, the memory during hypnosis of a like previous state, the carrying out of a post-hypnotic suggestion, etc. Suggestibility means in this case the capability of exciting this lower consciousness and the carrying over of the excited part into the higher consciousness. We may say in opposition to this view (1) that introspection, our only legitimate guide here, discovers to us only one kind of consciousness. (2) This "under" consciousness, as the depository of elements of a jack-in-the-box character, gives us a problem in retention and recall, and not in the ultimate nature of consciousness.

The primary fact from which we must start is that consciousness is not a homogeneous unity, but falls under analysis into more or less distinct divisions. Of these, certain ones as sensations and ideas, can be traced with considerable facility, perhaps because of their partial abstractness. The more complex divisions present themselves as groups of ideas held together by what are called associative and apperceptive connections. These groups are permanent in proportion to the closeness of the internal connections. Consciousness as a whole, reacting through the process of attention upon any particular group, gives to it, or apparently discovers in it, a certain degree of self-dependence and distinctness. What we mean when speaking of the normal mind is, that each group has its relative strength or significance in consciousness, and, resulting from this, a certain degree of facility in associating itself with and passing over into other groups. In many pathological states and in hypnosis, undue significance is given to one or more groups, resulting, in the first case, in fixed ideas or insane delusions, and, in the latter case, a narrowed consciousness and cramped attention which gives to the group complete dominance for the time being.

The excitation of such a group is all that can be meant by suggestion in hypnosis.

1. Revue Philosophique, XXII., p. 677. 2. Das Doppel-Ich. 3. Der Hyp-, notismus.

What are we to conclude then in regard to suggestibility! (1) That no fact is included in the term of such unusual significance that it must lead to a revision of the ordinary well' grounded psychological views. This is the mistake of most theorists along this line. (2) As the term has hitherto been employed, it applies to the excitation of a part of consciousness. (3) That there is no difference in kind between suggestibility in normal and in hypnotic states. There is the same process of sensory excitation and the same supplementation through the association of ideas. The question why consciousness is narrowed in such a way as to give dominance to a particular group is the problem for the general theory of hypnotism. This narrowing of consciousness, however, has some very important effects upon the degree of suggestibility, which should be mentioned. (1) As was stated above, suggestion is the excitation of a part of consciousness. The general rule may be stated that in proportion as consciousness, becomes narrowed down to some particular group, the excitability of this group, and so suggestibility, increases. (2) Another general rule is that in proportion as the excitability of any particular group increases, the excitability of other and especially opposing groups decreases.

This may be seen in the anaesthesia and catalepsy of hypnosis. (3) The attitude of the attention in expectation is very imperfectly understood, but, whatever it may be, it is closely related to the two above mentioned facts, and plays an important part in suggestibility. One of the peculiar, aspects of the hypnotic condition is a certain readiness in the re-ceptivity of any stimulus, and the apparent indifference in the effect as to what particular group shall become dominant. (4) Another important question in hypnotic suggestibility is that of rapport. From the standpoint of psychology all we can say is, that the idea of the hypnotizer is, from the beginning of the condition, the dominant element in the consciousness of the subject, and forms the starting point from which the excitation of other groups goes out.