805. As a first step in our analysis, we may point out certain main characters which unite in a true class all the automatisms which we are here considering - greatly though these may differ among themselves in external form.

In the first place, then, our automatisms are independent phenomena; they are what the physician calls idiognomonic. That is to say, they are not merely symptomatic of some other affection, or incidental to some pro-founder change. The mere fact, for instance, that a man writes messages which he does not consciously originate will not, when taken alone, prove anything beyond this fact itself as to the writer's condition. He may be perfectly sane, in normal health, and with nothing unusual observable about him. This characteristic - provable by actual observation and experiment - distinguishes our automatisms from various seemingly kindred phenomena. Thus we may have to include in our class the occasional automatic utterance of words or sentences. But the continuous exhausting vociferation of acute mania does not fall within our province; for those shouts are merely symptomatic; nor, again, does the cri hydrocephalique (or spontaneous meaningless noise which sometimes accompanies water on the brain); for that, too, is no independent phenomenon, but the direct consequence of a definite lesion. Furthermore, we shall have to include in our class certain simple movements of the hands, co-ordinated into the act of writing.

But here, also, our definition will lead us to exclude choreic movements, which are merely symptomatic of nervous mal-nutri-tion; or which we may, if we choose, call idiopathic, as constituting an independent malady. But our automatisms are not idiopathic but idiognomonic; they may indeed be associated with or facilitated by certain states of the organism, but they are neither a symptom of any other malady, nor are they a malady in themselves.

Agreeing, then, that our peculiar class consists of automatisms which are idiognomonic, - whose existence does not necessarily imply the existence of some profounder affection already known as producing them, - we have still to look for some more positive bond of connection between them some quality common to all of them, and which makes them worth our prolonged investigation.

This we shall find in the fact that they are all of them message-bearing or nunciative automatisms. I do not, of course, mean that they all of them bring messages from sources external to the automatist's own mind. In some cases they probably do this; but as a rule the so-called messages seem more probably to originate within the automatist's own personality. Why, then, it may be asked, do I call them messages? We do not usually speak of a man as sending a message to himself. The answer to this question involves, as we shall presently see, the profoundest conception of these automatisms to which we can as yet attain. They present themselves to us as messages communicated from one stratum to another stratum of the same personality. Originating in some deeper zone of a man's being, they float up into superficial consciousness as deeds, visions, words, ready-made and full-blown, without any accompanying perception of the elaborative process which has made them what they are.

806. Can we then (we may next ask) in any way predict the possible range of these motor automatisms? Have we any limit assignable a priori, outside which it would be useless to look for any externalisation of an impulse emanating from sub-conscious strata of our being?

The answer to this must be that no such limit can be with any confidence suggested. We have not yet learnt with any distinctness even how far the wave from a consciously-perceived stimulus will spread, or what changes its motion will assume. Still less can we predict the limitations which the resistance of the organism will impose on the radiation of a stimulus originated within itself. We are learning to consider the human organism as a practically infinite complex of interacting vibrations; and each year adds many new facts to our knowledge of the various transformations which these vibrations may undergo, and of the unexpected artifices by which we may learn to cognise some stimulus which is not directly felt.

A few concrete instances will make my meaning plainer. And my first example shall be taken from those experiments in muscle-reading - less correctly termed mind-reading - with which the readers of these Proceedings are already familiar. Let us suppose that I am to hide a pin, and that some accomplished muscle-reader is to take my hand and find the pin by noting my muscular indications.1 I first hide the pin in the hearth-rug; then I change my mind and hide it in the bookshelf. I fix my mind on the bookshelf, but resolve to make no guiding movement. The muscle-reader takes my hand, leads me first to the rug, then to the bookshelf, and finds the pin. Now, what has happened in this case? What movements have I made?

Firstly, I have made no voluntary movement; and secondly, I have made no conscious involuntary movement. But, thirdly, I have made an unconscious involuntary movement which directly depended on conscious ideation. I strongly thought of the bookshelf, and when the bookshelf was reached in our vague career about the room I made a movement - say rather a tremor occurred - in my hand, which, although beyond both my knowledge and my control, was enough to supply to the muscle-reader's delicate sensibility all the indication required. All this is now admitted, and, in a sense, understood; we formulate it by saying that my conscious ideation contained a motor element; and that this motor element, though inhibited from any conscious manifestation, did yet inevitably externalise itself in a peripheral tremor.

1 See, for instance, Proceedings S.P.R., vol. i. p. 291.

But, fourthly, something more than this has clearly taken place. Before the muscle-reader stopped at the bookshelf he stopped at the rug. I was no longer consciously thinking of the rug; but the idea of the pin in the rug must still have been reverberating, so to say, in my sub-conscious region; and this unconscious memory, this unnoted reverberation, revealed itself in a peripheral tremor nearly as distinct as that which (when the bookshelf was reached) corresponded to the strain of conscious thought.

This tremor, then, was in a certain sense a message-bearing automatism. It was the externalisation of an idea which, once conscious, had become unconscious, though in the slightest conceivable degree - namely, by a mere slight escape from the field of direct attention.