It remains then for me, first to state wherein Hartley differs from Aristotle; then, to exhibit the grounds of my conviction, that he differed only to err: and next as the result, to show, by what influences of the choice and judgment the associative power becomes either memory or fancy; and, in conclusion, to appropriate the remaining offices of the mind to the reason, and the imagination. With my best efforts to be as perspicuous as the nature of language will permit on such a subject, I earnestly solicit the good wishes and friendly patience of my readers, while I thus go "sounding on my dim and perilous way."
CHAPTER VI
That Hartley's system, as far as it differs from that of Aristotle, is neither tenable in theory, nor founded in facts.
Of Hartley's hypothetical vibrations in his hypothetical oscillating ether of the nerves, which is the first and most obvious distinction between his system and that of Aristotle, I shall say little. This, with all other similar attempts to render that an object of the sight which has no relation to sight, has been already sufficiently exposed by the younger Reimarus, Maasz, and others, as outraging the very axioms of mechanics in a scheme, the merit of which consists in its being mechanical. Whether any other philosophy be possible, but the mechanical; and again, whether the mechanical system can have any claim to be called philosophy; are questions for another place. It is, however, certain, that as long as we deny the former, and affirm the latter, we must bewilder ourselves, whenever we would pierce into the adyta of causation; and all that laborious conjecture can do, is to fill up the gaps of fancy. Under that despotism of the eye (the emancipation from which Pythagoras by his numeral, and Plato by his musical, symbols, and both by geometric discipline, aimed at, as the first propaideuma of the mind)—under this strong sensuous influence, we are restless because invisible things are not the objects of vision; and metaphysical systems, for the most part, become popular, not for their truth, but in proportion as they attribute to causes a susceptibility of being seen, if only our visual organs were sufficiently powerful.
From a hundred possible confutations let one suffice. According to this system the idea or vibration a from the external object A becomes associable with the idea or vibration m from the external object M, because the oscillation a propagated itself so as to re-produce the oscillation m. But the original impression from M was essentially different from the impression A: unless therefore different causes may produce the same effect, the vibration a could never produce the vibration m: and this therefore could never be the means, by which a and m are associated. To understand this, the attentive reader need only be reminded, that the ideas are themselves, in Hartley's system, nothing more than their appropriate configurative vibrations. It is a mere delusion of the fancy to conceive the pre-existence of the ideas, in any chain of association, as so many differently coloured billiard-balls in contact, so that when an object, the billiard-stick, strikes the first or white ball, the same motion propagates itself through the red, green, blue and black, and sets the whole in motion. No! we must suppose the very same force, which constitutes the white ball, to constitute the red or black; or the idea of a circle to constitute the idea of a triangle; which is impossible.
But it may be said, that by the sensations from the objects A and M, the nerves have acquired a disposition to the vibrations a and m, and therefore a need only be repeated in order to re-produce m. Now we will grant, for a moment, the possibility of such a disposition in a material nerve, which yet seems scarcely less absurd than to say, that a weather-cock had acquired a habit of turning to the east, from the wind having been so long in that quarter: for if it be replied, that we must take in the circumstance of life, what then becomes of the mechanical philosophy? And what is the nerve, but the flint which the wag placed in the pot as the first ingredient of his stone broth, requiring only salt, turnips, and mutton, for the remainder! But if we waive this, and pre-suppose the actual existence of such a disposition; two cases are possible. Either, every idea has its own nerve and correspondent oscillation, or this is not the case. If the latter be the truth, we should gain nothing by these dispositions; for then, every nerve having several dispositions, when the motion of any other nerve is propagated into it, there will be no ground or cause present, why exactly the oscillation m should arise, rather than any other to which it was equally pre-disposed. But if we take the former, and let every idea have a nerve of its own, then every nerve must be capable of propagating its motion into many other nerves; and again, there is no reason assignable, why the vibration m should arise, rather than any other ad libitum.
It is fashionable to smile at Hartley's vibrations and vibratiuncles; and his work has been re-edited by Priestley, with the omission of the material hypothesis. But Hartley was too great a man, too coherent a thinker, for this to have been done, either consistently or to any wise purpose. For all other parts of his system, as far as they are peculiar to that system, once removed from their mechanical basis, not only lose their main support, but the very motive which led to their adoption. Thus the principle of contemporaneity, which Aristotle had made the common condition of all the laws of association, Hartley was constrained to represent as being itself the sole law. For to what law can the action of material atoms be subject, but that of proximity in place? And to what law can their motions be subjected but that of time? Again, from this results inevitably, that the will, the reason, the judgment, and the understanding, instead of being the determining causes of association, must needs be represented as its creatures, and among its mechanical effects. Conceive, for instance, a broad stream, winding through a mountainous country with an indefinite number of currents, varying and running into each other according as the gusts chance to blow from the opening of the mountains. The temporary union of several currents in one, so as to form the main current of the moment, would present an accurate image of Hartley's theory of the will.
Had this been really the case, the consequence would have been, that our whole life would be divided between the despotism of outward impressions, and that of senseless and passive memory. Take his law in its highest abstraction and most philosophical form, namely, that every partial representation recalls the total representation of which it was a part; and the law becomes nugatory, were it only for its universality. In practice it would indeed be mere lawlessness. Consider, how immense must be the sphere of a total impression from the top of St. Paul's church; and how rapid and continuous the series of such total impressions. If, therefore, we suppose the absence of all interference of the will, reason, and judgment, one or other of two consequences must result. Either the ideas, or reliques of such impression, will exactly imitate the order of the impression itself, which would be absolute delirium: or any one part of that impression might recall any other part, and—(as from the law of continuity, there must exist in every total impression, some one or more parts, which are components of some other following total impression, and so on ad infinitum)—any part of any impression might recall any part of any other, without a cause present to determine what it should be. For to bring in the will, or reason, as causes of their own cause, that is, as at once causes and effects, can satisfy those only who, in their pretended evidences of a God, having first demanded organization, as the sole cause and ground of intellect, will then coolly demand the pre-existence of intellect, as the cause and ground-work of organization. There is in truth but one state to which this theory applies at all, namely, that of complete light-headedness; and even to this it applies but partially, because the will and reason are perhaps never wholly suspended.
A case of this kind occurred in a Roman Catholic town in Germany a year or two before my arrival at Goettingen, and had not then ceased