chapter I
shall consider this case. Here I content myself with saying that it does not seem conclusive as to the point at issue; and that I still believe association of coexistent or sequent impressions to be the one _elementary_ law.
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CONTRAST _has also been held to be an independent agent in association._ But the reproduction of an object contrasting with one already in the mind is easily explained on our principles. Recent writers, in fact, all reduce it either to similarity or contiguity. Contrast always presupposes generic similarity; it is only the _extremes of a class_ which are contrasted, black and white, not black and sour, or white and prickly. A machinery which reproduces a similar at all, may reproduce the _opposite_ similar, as well as any intermediate term. Moreover, the greater number of contrasts are habitually coupled in speech, young and old, life and death, rich and poor, etc., and are, as Dr. Bain says, in everybody's memory.[492]
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I trust that the student will now feel that the way to a deeper understanding of the order of our ideas lies in the direction of cerebral physiology. The _elementary_ process of revival can be nothing but the law of habit. Truly the day is distant when physiologists shall actually trace from cell-group to cell-group the irradiations which we have hypothetically invoked. Probably it will never arrive. The schematism we have used is, moreover, taken immediately from the analysis of objects into their elementary parts, and only extended by analogy to the brain. And yet it is only as incorporated in the brain that such a schematism can represent anything _causal_. This is, to my mind, the conclusive reason for saying that the order of _presentation of the mind's materials_ is due to cerebral physiology alone.
The law of accidental prepotency of certain processes over others falls also within the sphere of cerebral probabilities. Granting such instability as the brain-tissue requires, certain points must always discharge more quickly and strongly than others; and this prepotency would shift its place from moment to moment by accidental causes, giving us a perfect mechanical diagram of the capricious play of similar association in the most gifted mind. The study of dreams confirms this view. The usual abundance of paths of irradiation seems, in the dormant brain, reduced. A few only are pervious, and the most fantastic sequences occur because the currents run--'like sparks in burnt-up paper'--wherever the nutrition of the moment creates an opening, but nowhere else.
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The _effects of interested attention and volition_ remain. These
## activities seem to hold fast to certain elements, and by emphasizing
them and dwelling on them, to make their associates the only ones which are evoked. _This_ is the point at which an anti-mechanical psychology must, if anywhere, make it stand in dealing with association. Everything else is pretty certainly due to cerebral laws. My own opinion on the question of active attention and spiritual spontaneity is expressed elsewhere. But even though there be a mental spontaneity, it can certainly not create ideas or summon them _ex abrupto_. Its power is limited to _selecting_ amongst those which the associative machinery has already introduced or tends to introduce. If it can emphasize, reinforce, or protract for a second either one of these, it can do all that the most eager advocate of free will need demand; for it then decides the direction of the next associations by making them hinge upon the emphasized term; and determining in this wise the course of the man's thinking, it also determines his acts.
THE HISTORY OF OPINION CONCERNING ASSOCIATION
may be briefly glanced at ere we end the chapter.[493] Aristotle seems to have caught both the facts and the principle of explanation; but he did not expand his views, and it was not till the time of Hobbes that the matter was again touched on in a definite way. Hobbes first formulated the problem of the succession of our thoughts. He writes in Leviathan,