FUETHER PEOBLEMS OF HYPNOTISM. (l.) 225

might be held to be directly due, though dissimilar, to the cerebral events in A, or (2) some prior and equally dissimilar cerebral event in B, accompanied by some unknown psychosis dissimilar to A's (e.g., some mood or mode of feeling presenting nothing of the nature of idea), might be assumed as an intervening link. 1 As regards this notion of an unknown psychosis, if a priori likelihoods had any application to modes of psychical interaction, one might at any rate feel it unlikely that terminal events so closely related as B's trance and A's desire for B's trance should be causally connected by an unknown psychical state resembling neither ; but I should be content to urge that the hypothesis is gratuitous, when we remember that there is one known psychical state which is known also to lead on naturally to trance namely, that idea of trance, the unique effect of which can be so completely tested by verbal suggestion. But a graver objection and one which applies to both the above hypotheses alike lies in the nature of the physical assumption. No doubt, it may be said that anyone who can entertain for a moment the idea of brain acting on brain at a distance has no business with speculative scruples that, finding himself upon such unknown ground, he need not hesitate to go further, and imagine a complete difference between the physical cause and the physical effect. But even if a needless step were justified merely by being taken in the dark, we should at least observe that this particular step breaks away, not only from the analogy of verbal suggestion, but from the only conception of a physical nexus which has in any degree commended the hypothesis of physical communication between brain and brain to scientific minds the conception suggested by the analogies of tuning-forks, communicated light-vibrations, induced magnetism and induced electric currents. 2 If that con- 1 A third alternative is possible that some cerebral condition in A (e.g. t a certain initiatory tendency towards trance in himself) is reproduced in B, without psychosis. This would still leave clear my fundamental distinction (depending on similarity of primary effect in recipient to cause in agent) between telepathic communications and all others. But the reasons for regarding psychosis in B as probable are given a little later. 2 There are, of course, cases where vibratory energy does not reproduce, at the place where it takes effect, the exact form of its source : as where light produces chemical changes. But when it is remembered that the place of origin and place of action of the nervous force now in question are similar pieces of matter the same in their composition, in their form, and in the energies normally connected with them the other analogies seem paramount ; especially when we remember the electrical character now generally attributed to nerve- currents. 15