§ 3. Tendency of Motor Reproduction to pass into Actual Movement. — No one has done more than Dr. Bain to bring into prominence the importance of the motor constituents of ideas, and he has also laid great emphasis on the tendency of ideal movement to pass into actual movement. In the mental revival of experiences of energetic action, "it is," he says, "a notorious circumstance that, if there be much excitement attending the recollection, we can only with great difficulty prevent ourselves from getting up to repeat them. ... A child cannot describe anything that it was engaged in, without acting it out to the full length that the circumstances will permit. . . . No better example could be furnished than the vocal recollections. When we recall the impression of a word or a sentence, if we do not speak it out, we feel the twitter of the organs just about to come to that point. The articulating parts — the larynx, the tongue, the lips — are all sensibly excited. . . . Some persons of weak or incontinent nerves can hardly think without muttering — they talk to themselves." *

"Thinking is restrained speaking or acting." Since Dr. Bain first wrote these words, psychological investigation has very strongly confirmed their general purport. The tendency of ideas to act themselves out is now a commonplace of psychology. Probably Dr. Bain exaggerates the degree in which this tendency is ordinarily realised. The twitter of the organs of speech about to come to the point is not a constant feature of inward articulation in all persons. But there is no doubt that it is very frequent, and in some people almost invariably present. In what he says about thinking aloud, he rather understates his case ; this habit is by no means confined to persons of weak or incontinent nerves. It is often found in those who become intensely absorbed in their own trains of thought to the disregard of their social surroundings. Social convention has a great deal to do with the restraint which we ordinarily put on the actual utterance of the thoughts which pass through our minds.

* The Senses and the Intellect, fourth edition, p. 357. Op. cit., p. 358.

The general theory of the tendency of ideas to pass into movements is as follows. Ideational process is correlated with brain process. The brain is so intimately one with the rest of the organism, that processes in it cannot take place without in some measure overflowing to other parts of the body; and in particular to those parts with which it is most directly connected — the muscles. The whole complex apparatus of efferent nerves creates a functional unity between brain and muscle. This overflow of excitation to the muscles may, and constantly does, take place without the subject being at all aware of it. Thus in thoughtreading the place where an object has been hidden is revealed to the thoughtreader by slight muscular pressures and twitches unconsciously produced by his guide, who all the time concentrates his attention on the idea of the hidden object and the place where it is to be found.

On the whole, at the level of our present mental development, ideational trains of thought proceed for the most part without any distinct and conspicuous embodiment in actual movement, unless a need arises for communicating them to others. But the conditions are very different in more primitive stages of evolution. Where ideational activity is just struggling into independent existence, so that it may be regarded as little more than an extension or supplement of perceptual activity, ideas can scarcely fail to pass into overt movements. The more life in general is a life of bodily activity, the more likely is bodily activity to enter into ideal process. Besides this, we must remember that the less developed and habitual are trains of thought, the more difficult they are to sustain; so that whatever means offer themselves for the furtherance and support of the process will be utilised. But the partial repetition of the ideally represented object by means of actual movements yields a ready and effective means of fixing attention on the object. Hence we may regard the actual expression of ideas by movements as primary, and the absence of such expression as the result of a comparatively high degree of mental development.*

But even if we suppose that the tendency to act out an idea does not find distinct realisation in the individual's own private trains of thought, it must do so when occasion arises to communicate with others. Suppose that A and B are cooperating in some important work. It is B's turn to do something, and A's to wait expectantly. B either fails to do what is required of him or does it wrongly. Suppose that A has no conventional language to express himself in, or even that he has not used language of any sort until that moment. If he is capable of ideally representing what he wants B to do, he can scarcely fail in his impatient eagerness to make movements indicating what is required. It may be sufficient to point to some object actually present. This does not strictly speaking involve the use of language. But if he uses a truly imitative gesture or combination of imitative gestures, then his action is the birth of language. He may, for instance, point to a rope and imitate the act of hauling. The imitation of the act of hauling is simply his own idea of hauling issuing in actual movement. Thus from a psychological point of view the most primitive form of language is the imitative gesture. We shall now proceed to give evidence in favour of this position.

* "I fancy the main body of the lower classes of Africa think externally instead of internally . . . even when you are sitting alone in the forest you will hear a man or woman coming down the narrow bush path chattering away with such energy and expression that you can hardly believe your eyes when you learn from them that he has no companion." M. H. Kingsley, West African Studies.