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CHAPTER III.

THE ORIGIN OF THE IMPRESSIONS.

ADMITTING that the sensations, the feelings of pleasure and pain, and those of relation, are the primary irresolvable states of consciousness, two further lines of investigation present themselves. The one leads us to seek the origin of these "impressions; " the other, to inquire into the nature of the steps by which they become metamorphosed into those compound states of consciousness, which so largely enter into our ordinary trains of thought.

With respect to the origin of impressions of sensation, Hume is not quite consistent with himself. In one place (I. p. 117) he says, that it is impossible to decide "whether they arise immediately from the object, or are produced by the creative power of the mind, or are derived from the Author of our being," thereby implying that realism and idealism are equally probable hypotheses. But, in fact, after the demonstration by Descartes, that the immediate antecedents of sensations are changes in the nervous system, with which our feelings have no sort of resemblance, the hypothesis that sensations "arise immediately from the object" was out of court;

and that Hume fully admitted the Cartesian doctrine is apparent when he says (1. p. 272) :—

"All our perceptions are dependent on our organs and the disposition of our nerves and animal spirits."

And again, though in relation to another question, he observes :

:

"There are three different kinds of impressions conveyed by the senses. The first are those of the figure, bulk, motion, and solidity of bodies. The second those of colours, tastes, smells, sounds, heat, and cold. The third are the pains and pleasures that arise from the application of objects to our bodies, as by the cutting of our flesh with steel, and such like. Both philosophers and the vulgar suppose the first of these to have a distinct continued existence. The vulgar only regard the second as on the same footing. Both philosophers and the vulgar again esteem the third to be merely perceptions, and consequently interrupted and dependent beings.

"Now 'tis evident that, whatever may be our philosophical opinion, colour, sounds, heat, and cold, as far as appears to the senses, exist after the same manner with motion and solidity; and that the difference we make between them, in this respect, arises not from the mere perception. So strong is the prejudice for the distinct continued existence of the former qualities, that when the contrary opinion is advanced by modern philosophers, people imagine they can almost refute it from their reason and experience, and that their very senses contradict this philosophy. "Tis also evident that colours, sounds, &c., are originally on the same footing with the pain that arises from steel, and pleasure that proceeds from a fire; and that the difference betwixt them is founded neither on perception nor reason, but on the imagination. For as they are confessed to be, both of them, nothing but perceptions arising from the particular configurations and motions of the parts of body, wherein possibly can their difference consist? Upon the whole, then, we may conclude that, as far as

the senses are judges, all perceptions are the same in the manner of their existence.”—(I. p. 250, 251.)

The last words of this passage are as much Berkeley's as Hume's. But, instead of following Berkeley in his deductions from the position thus laid down, Hume, as the preceding citation shows, fully adopted the conclusion to which all that we know of psychological physiology tends, that the origin of the elements of consciousness, no less than that of all its other states, is to be sought in bodily changes, the seat of which can only be placed in the brain. And, as Locke had already done with less effect, he states and refutes the arguments commonly brought against the possibility of a causal connexion between the modes of motion of the cerebral substance and states of consciousness, with great clearness :

"From these hypotheses concerning the substance and local conjunction of our perceptions we may pass to another, which is more intelligible than the former, and more important than the latter, viz. concerning the cause of our perceptions. Matter and motion, 'tis commonly said in the schools, however varied, are still matter and motion, and produce only a difference in the position and situation of objects. Divide a body as often as you please, 'tis still body. Place it in any figure, nothing ever results but figure, or the relation of parts. Move it in any manner, you still find motion or a change of relation. 'Tis absurd to imagine that motion in a circle, for instance, should be nothing but merely motion in a circle; while motion in another direction, as in an ellipse, should also be a passion or moral reflection; that the shocking of two globular particles should become a sensation of pain, and that the meeting of the triangular ones should afford a pleasure. Now as these different shocks and variations and mixtures are the only changes of which matter is

susceptible, and as these never afford us any idea of thought or perception, 'tis concluded to be impossible, that thought can ever be caused by matter.

"Few have been able to withstand the seeming evidence of this argument; and yet nothing in the world is more easy than to refute it. We need only reflect upon what has been proved at large, that we are never sensible of any connexion between causes and effects, and that 'tis only by our experience of their constant conjunction we can arrive at any knowledge of this relation. Now, as all objects which are not contrary are susceptible of a constant conjunction, and as no real objects are contrary, I have inferred from these principles (Part III. § 15) that, to consider the matter a priori, anything may produce anything, and that we shall never discover a reason why any object may or may not be the cause of any other, however great, or however little, the resemblance may be betwixt them. This evidently destroys the precedent reasoning, concerning the cause of thought or perception. For though there appear no manner of connection betwixt motion and thought, the case is the same with all other causes and effects. Place one body of a pound weight on one end of a lever, and another body of the same weight on the other end; you will never find in these bodies any principle of motion dependent on their distance from the centre, more than of thought and perception. If you pretend, therefore, to prove, a priori, that such a position of bodies can never cause thought, because, turn it which way you will, it is nothing but a position of bodies: you must, by the same course of reasoning, conclude that it can never produce motion, since there is no more apparent connection in the one than in the other. But, as this latter conclusion is contrary to evident experience, and as 'tis possible we may have a like experience in the operations of the mind, and may perceive a constant conjunction of thought and motion, you reason too hastily when, from the mere consideration of the ideas, you conclude that 'tis impossible motion can ever produce thought, or a different position of parts give rise to a different passion or reflection. Nay, 'tis not only possible we may have such

an experience, but 'tis certain we have it; since every one may perceive that the different dispositions of his body change his thoughts and sentiments. And should it be said that this depends on the union of soul and body, I would answer, that we must separate the question concerning the substance of the mind from that concerning the cause of its thought; and that, confining ourselves to the latter question, we find, by the comparing their ideas, that thought and motion are different from each other and by experience, that they are constantly united; which, being all the circumstances that enter into the idea of cause and effect, when applied to the operations of matter, we may certainly conclude that motion may be, and actually is, the cause of thought and perception." -(I. pp. 314-316.)

The upshot of all this is, that the "collection of perceptions," which constitutes the mind, is really a system of effects, the causes of which are to be sought in antecedent changes of the matter of the brain, just as the "collection of motions," which we call flying, is a system of effects, the causes of which are to be sought in the modes of motion of the matter of the muscles of the wings.

Hume, however, treats of this important topic only incidentally. He seems to have had very little acquaintance even with such physiology as was current in his time. At least, the only passage of his works, bearing on this subject, with which I am acquainted, contains nothing but a very odd version of the physiological views of Descartes:

"When I received the relations of resemblance, contiguity, and causation, as principles of union among ideas, without examining into their causes, 'twas more in prosecution of my first maxim, that we must in the end rest contented with experience, than for want of something specious and plausible which I might have displayed on that subject. 'Twould

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