807. Having, then, considered an instance where the automatic message passes only between two closely-adjacent strata of consciousness, externalising an impulse derived from an idea which has only recently sunk out of consciousness and which could easily be summoned back again; - let us find our next illustration in a case where the line of demarcation between the strata of consciousness through which the automatic message pierces is distinct and impassable by any effort of will.

Let us take a case of post-hypnotic suggestion - say, for instance, an experiment of Edmund Gurney's (see Proceedings S.P.R., vol. iv. p. 319). The subject had been trained to write with planchette, after he had been awakened, the statements which had been made to him when in the hypnotic trance. He wrote the desired words, or something like them, but while he wrote them his waking self was entirely unaware of what his hand was writing. Thus, having been told in the trance, "It has begun snowing again," he wrote after waking, "It begun snowing," while he read aloud, with waking intelligence, from a book of stories, and was quite unconscious of what his hand (placed on a planchette behind a screen) was at the same time writing.

Here we have an automatic message of traceable origin; a message implanted in the hypnotic stratum of the subject's self, and cropping up - like a fault - in the waking stratum, - externalised in automatic movements which the waking self could neither predict nor guide.

808. Yet once more. In the discussion which will follow we shall have various instances of the transformation (as I shall regard it) of psychical shock into definite muscular energy of apparently a quite alien kind. Such transformations of so-called psychical into physical force - of will into motion - do of course perpetually occur within us. But the nature of these is commonly much obscured by the problem as to the true efficacy of the will; and it seems desirable to cite one or two examples of such transmutation where the process is what we call automatic, and we seem to detect the simple muscular correlative - the motor equivalent - to some emotion or sensation which contains no obvious motor element at all.

An easy, though a rough, way of testing transmutations of this kind is afforded by the dynamometer. It is necessary first to discover the amount of pressure which the subject of experiment can exert on the dynamometer, by squeezing it with all the force at his command, in his ordinary condition. After he has had a little practice his highest attainable force of squeeze becomes nearly constant; and it is then possible to subject him to various stimuli, and to measure the degree of response; that is, the degree in which his squeeze becomes either more or less powerful while the stimulus is applied. The experiments are, in fact, a sort of elaboration of a familiar phenomenon. I take a child to a circus; he sits by me holding my hand; there is a discharge of musketry and his grip tightens. Now in this case we should call the child's tightened grip automatic. But suppose that, instead of merely holding my hand, he is trying with all his might to squeeze the dynamometer, and that the sudden excitation enables him to squeeze it harder - are we then to describe that extra squeeze as automatic? or as voluntary?

However phrased, it is the fact (as amply established by M. Fere and others1) that excitations of almost any kind - whether sudden and startling or agreeable and prolonged - do tend to increase the subject's dynamometrical power. In the first place, and this is in itself an important fact, the average of squeezing-power is found to be greater among educated students than among robust labouring men, thus showing that it is not so much developed muscle as active brain which renders possible a sudden concentration of muscular force. But more than this; M. Fere finds that with himself and his friends the mere listening to an interesting lecture, or the mere stress of thought in solitude, or still more the act of writing or of speech, produces a decided increase of strength in the grip, especially of the right hand. The same effect of dynamogeny is produced with hypnotic subjects, by musical sounds, by coloured light, especially red light, and even by a hallucinatory suggestion of red light. "All our sensations," says M. Fere in conclusion, "are accompanied by a development of potential energy, which passes into a kinetic state, and externalises itself in motor manifestations which even so rough a method as dynamo-metry is able to observe and record".

1 Sensation et Mouvement, par Ch. Fere. Paris: Alcan, 1887.

I would beg the reader to keep these words in mind. We shall presently find that a method apparently even rougher than dynamographic tracings may be able to interpret, with far greater delicacy, the automatic tremors which are coursing to and fro within us. If once we can get a spy into the citadel of our own being, his rudest signalling will tell us more than our subtlest inferences from outside of what is being planned and done within.