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CHAPTER V

On the law of Association—Its history traced from Aristotle to Hartley.

There have been men in all ages, who have been impelled as by an instinct to propose their own nature as a problem, and who devote their attempts to its solution. The first step was to construct a table of distinctions, which they seem to have formed on the principle of the absence or presence of the Will. Our various sensations, perceptions, and movements were classed as active or passive, or as media partaking of both. A still finer distinction was soon established between the voluntary and the spontaneous. In our perceptions we seem to ourselves merely passive to an external power, whether as a mirror reflecting the landscape, or as a blank canvass on which some unknown hand paints it. For it is worthy of notice, that the latter, or the system of Idealism may be traced to sources equally remote with the former, or Materialism; and Berkeley can boast an ancestry at least as venerable as Gassendi or Hobbes. These conjectures, however, concerning the mode in which our perceptions originated, could not alter the natural difference of Things and Thoughts. In the former, the cause appeared wholly external, while in the latter, sometimes our will interfered as the producing or determining cause, and sometimes our nature seemed to act by a mechanism of its own, without any conscious effort of the will, or even against it. Our inward experiences were thus arranged in three separate classes, the passive sense, or what the School-men call the merely receptive quality of the mind; the voluntary; and the spontaneous, which holds the middle place between both. But it is not in human nature to meditate on any mode of action, without inquiring after the law that governs it; and in the explanation of the spontaneous movements of our being, the metaphysician took the lead of the anatomist and natural philosopher. In Egypt, Palestine, Greece, and India the analysis of the mind had reached its noon and manhood, while experimental research was still in its dawn and infancy. For many, very many centuries, it has been difficult to advance a new truth, or even a new error, in the philosophy of the intellect or morals. With regard, however, to the laws that direct the spontaneous movements of thought and the principle of their intellectual mechanism there exists, it has been asserted, an important exception most honourable to the moderns, and in the merit of which our own country claims the largest share. Sir James Mackintosh,—(who, amid the variety of his talents and attainments, is not of less repute for the depth and accuracy of his philosophical inquiries than for the eloquence with which he is said to render their most difficult results perspicuous, and the driest attractive,)—affirmed in the Lectures, delivered by him in Lincoln's Inn Hall, that the law of association as established in the contemporaneity of the original impressions, formed the basis of all true psychology; and that any ontological or metaphysical science, not contained in such (that is, an empirical) psychology, was but a web of abstractions and generalizations. Of this prolific truth, of this great fundamental law, he declared Hobbes to have been the original discoverer, while its full application to the whole intellectual system we owed to Hartley; who stood in the same relation to Hobbes as Newton to Kepler; the law of association being that to the mind, which gravitation is to matter.

Of the former clause in this assertion, as it respects the comparative merits of the ancient metaphysicians, including their commentators, the School-men, and of the modern and British and French philosophers from Hobbes to Hume, Hartley, and Condillac, this is not the place to speak. So wide indeed is the chasm between Sir James Mackintosh's philosophical creed and mine, that so far from being able to join hands, we could scarcely make our voices intelligible to each other: and to bridge it over would require more time, skill, and power than I believe myself to possess. But the latter clause involves for the greater part a mere question of fact and history, and the accuracy of the statement is to be tried by documents rather than reasoning.

First, then, I deny Hobbes's claim in toto: for he had been anticipated by Des Cartes, whose work De Methodo, preceded Hobbes's De Natura Humana, by more than a year. But what is of much more importance, Hobbes builds nothing on the principle which he had announced. He does not even announce it, as differing in any respect from the general laws of material motion and impact: nor was it, indeed, possible for him so to do, compatibly with his system, which was exclusively material and mechanical. Far otherwise is it with Des Cartes; greatly as he too in his after writings (and still more egregiously his followers De la Forge, and others) obscured the truth by their attempts to explain it on the theory of nervous fluids, and material configurations. But, in his interesting work, De Methodo, Des Cartes relates the circumstance which first led him to meditate on this subject, and which since then has been often noticed and employed as an instance and illustration of the law. A child who with its eyes bandaged had lost several of his fingers by amputation, continued to complain for many days successively of pains, now in this joint and now in that, of the very fingers which had been cut off. Des Cartes was led by this incident to reflect on the uncertainty with which we attribute any particular place to any inward pain or uneasiness, and proceeded after long consideration to establish it as a general law: that contemporaneous impressions, whether images or sensations, recall each other mechanically. On this principle, as a ground work, he built up the whole system of human language, as one continued process of association. He showed in what sense not only general terms, but generic images,—under the name of abstract ideas,—actually existed, and in what consist their nature and power. As one word may become the general exponent of many, so by association a simple image may represent a whole class. But in truth Hobbes himself makes no claims to any discovery, and introduces this law of association, or (in his own language) discursion of mind, as an admitted fact, in the solution alone of which, and this by causes purely physiological, he arrogates any originality. His system is briefly this; whenever the senses are impinged on by external objects, whether by the rays of light reflected from them, or by effluxes of their finer particles, there results a correspondent motion of the innermost and subtlest organs. This motion constitutes a representation, and there remains an impression of the same, or a certain disposition to repeat the same motion. Whenever we feel several objects at the same time, the impressions that are left, (or in the language of Mr. Hume, the ideas,) [24] are linked together. Whenever therefore any one of the movements, which constitute a complex impression, is renewed through the senses, the others succeed mechanically. It follows of necessity, therefore, that Hobbes, as well as Hartley and all others who derive association from the connection and interdependence of the supposed matter, the movements of which constitute our thoughts, must have reduced all its forms to the one law of Time. But even the merit of announcing this law with philosophic precision cannot be fairly conceded to him. For the objects of any two ideas need not have co-existed in the same sensation in order to become mutually associable. The same result will follow when one only of the two ideas has been represented by the senses, and the other by the memory.

Long however before either Hobbes or Des Cartes the law of association had been defined, and its important functions set forth by Ludovicus Vives. Phantasia, it is to be noticed, is employed by Vives to express the mental power of comprehension, or the active function of the mind; and imaginatio for the receptivity (via receptiva) of impressions, or for the passive perception. The power of combination he appropriates to the former: "quae singula et simpliciter acceperat imaginatio, ea conjungit et disjungait phantasia." And the law by which the thoughts are spontaneously presented follows thus: "quae simul sunt a phantasia comprehensa, si alterutrum occurrat, solet secum alterum representare." To time therefore he subordinates all the other exciting causes of association. The soul proceeds "a causa ad effectum, ab hoc ad instrumentum, a parte ad totum;" thence to the place, from place to person, and from this to whatever preceded or followed, all as being parts of a total impression, each of which may recall the other. The apparent springs "saltus vel transitus etiam longissimos," he explains by the same thought having been a component part of two or more total impressions. Thus "ex Scipione venio in cogitationem potentiae Turcicae, propter victorias ejus de Asia, in qua regnabat Antiochus."

But from Vives I pass at once to the source of his doctrines, and (as far as we can judge from the remains yet extant of Greek philosophy) as to the first, so to the fullest and most perfect enunciation of the associative principle, namely, to the writings of Aristotle; and of these in particular to the treatises De Anima, and "De Memoria," which last belongs to the series of essays entitled in the old translations Parva Naturalia. In as much as later writers have either deviated from, or added to his doctrines, they appear to me to have introduced either error or groundless supposition.

In the first place it is to be observed, that Aristotle's positions on this subject are unmixed with fiction. The wise Stagyrite speaks of no successive particles propagating motion like billiard balls, as Hobbes; nor of nervous or animal spirits, where inanimate and irrational solids are thawed down, and distilled, or filtrated by ascension, into living and intelligent fluids, that etch and re-etch engravings on the brain, as the followers of Des Cartes, and the humoral pathologists in general; nor of an oscillating ether which was to effect the same service for the nerves of the brain considered as solid fibres, as the animal spirits perform for them under the notion of hollow tubes, as Hartley teaches—nor finally, (with yet more recent dreamers) of chemical compositions by elective affinity, or of an electric light at once the immediate object and the ultimate organ of inward vision, which rises to the brain like an Aurora Borealis, and there, disporting in various shapes,—as the balance of plus and minus, or negative and positive, is destroyed or re-established,—images out both past and present. Aristotle delivers a just theory without pretending to an hypothesis; or in other words a comprehensive survey of the different facts, and of their relations to each other without supposition, that is, a fact placed under a number of facts, as their common support and explanation; though in the majority of instances these hypotheses or suppositions better deserve the name of upopoiaeseis, or suffictions. He uses indeed the word kinaeseis, to express what we call representations or ideas, but he carefully distinguishes them from material motion, designating the latter always by annexing the words en topo, or kata topon. On the contrary, in his treatise De Anima, he excludes place and motion from all the operations of thought, whether representations or volitions, as attributes utterly and absurdly heterogeneous.

The general law of association, or, more accurately, the common condition under which all exciting causes act, and in which they may be generalized, according to Aristotle is this. Ideas by having been together acquire a power of recalling each other; or every partial representation awakes the total representation of which it had been a part. In the practical determination of this common principle to particular recollections, he admits five agents or occasioning causes: first, connection in time, whether simultaneous, preceding, or successive; second, vicinity or connection in space; third, interdependence or necessary connection, as cause and effect; fourth, likeness; and fifth, contrast. As an additional solution of the occasional seeming chasms in the continuity of reproduction he proves, that movements or ideas possessing one or the other of these five characters had passed through the mind as intermediate links, sufficiently clear to recall other parts of the same total impressions with which they had co-existed, though not vivid enough to excite that degree of attention which is requisite for distinct recollection, or as we may aptly express it, after consciousness. In association then consists the whole mechanism of the reproduction of impressions, in the Aristotelian Psychology. It is the universal law of the passive fancy and mechanical memory; that which supplies to all other faculties their objects, to all thought the elements of its materials.

In consulting the excellent commentary of St. Thomas Aquinas on the Parva Naturalia of Aristotle, I was struck at once with its close resemblance to Hume's Essay on Association. The main thoughts were the same in both, the order of the thoughts was the same, and even the illustrations differed only by Hume's occasional substitution of more modern examples. I mentioned the circumstance to several of my literary acquaintances, who admitted the closeness of the resemblance, and that it seemed too great to be explained by mere coincidence; but they thought it improbable that Hume should have held the pages of the Angelic Doctor worth turning over. But some time after Mr. Payne showed Sir James Mackintosh some odd volumes of St. Thomas Aquinas, partly perhaps from having heard that he had in his Lectures passed a high encomium on this canonized philosopher; but chiefly from the fact, that the volumes had belonged to Mr. Hume, and had here and there marginal marks and notes of reference in his own hand writing. Among these volumes was that which contains the Parva Naturalia, in the old Latin version, swathed and swaddled in the commentary afore mentioned

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 to be a frequent subject of conversation. A young woman of four or five and twenty, who could neither read, nor write, was seized with a nervous fever; during which, according to the asseverations of all the priests and monks of the neighbourhood, she became possessed, and, as it appeared, by a very learned devil. She continued incessantly talking Latin, Greek, and Hebrew, in very pompous tones and with most distinct enunciation. This possession was rendered more probable by the known fact that she was or had been a heretic. Voltaire humorously advises the devil to decline all acquaintance with medical men; and it would have been more to his reputation, if he had taken this advice in the present instance. The case had attracted the particular attention of a young physician, and by his statement many eminent physiologists and psychologists visited the town, and cross-examined the case on the spot. Sheets full of her ravings were taken down from her own mouth, and were found to consist of sentences, coherent and intelligible each for itself, but with little or no connection with each other. Of the Hebrew, a small portion only could be traced to the Bible; the remainder seemed to be in the Rabbinical dialect. All trick or conspiracy was out of the question. Not only had the young woman ever been a harmless, simple creature; but she was evidently labouring under a nervous fever. In the town, in which she had been resident for many years as a servant in different families, no solution presented itself. The young physician, however, determined to trace her past life step by step; for the patient herself was incapable of returning a rational answer. He at length succeeded in discovering the place, where her parents had lived: travelled thither, found them dead, but an uncle surviving; and from him learned, that the patient had been charitably taken by an old Protestant pastor at nine years old, and had remained with him some years, even till the old man's death. Of this pastor the uncle knew nothing, but that he was a very good man. With great difficulty, and after much search, our young medical philosopher discovered a niece of the pastor's, who had lived with him as his house-keeper, and had inherited his effects. She remembered the girl; related, that her venerable uncle had been too indulgent, and could not bear to hear the girl scolded; that she was willing to have kept her, but that, after her patron's death, the girl herself refused to stay. Anxious inquiries were then, of course, made concerning the pastor's habits; and the solution of the phenomenon was soon obtained. For it appeared, that it had been the old man's custom, for years, to walk up and down a passage of his house into which the kitchen door opened, and to read to himself with a loud voice, out of his favourite books. A considerable number of these were still in the niece's possession. She added, that he was a very learned man and a great Hebraist. Among the books were found a collection of Rabbinical writings, together with several of the Greek and Latin Fathers; and the physician succeeded in identifying so many passages with those taken down at the young woman's bedside, that no doubt could remain in any rational mind concerning the true origin of the impressions made on her nervous system.

This authenticated case furnishes both proof and instance, that reliques of sensation may exist for an indefinite time in a latent state, in the very same order in which they were originally impressed; and as we cannot rationally suppose the feverish state of the brain to act in any other way than as a stimulus, this fact (and it would not be difficult to adduce several of the same kind) contributes to make it even probable, that all thoughts are in themselves imperishable; and, that if the intelligent faculty should be rendered more comprehensive, it would require only a different and apportioned organization,—the body celestial instead of the body terrestrial,—to bring before every human soul the collective experience of its whole past existence. And this, this, perchance, is the dread book of judgment, in the mysterious hieroglyphics of which every idle word is recorded! Yea, in the very nature of a living spirit, it may be more possible that heaven and earth should pass away, than that a single act, a single thought, should be loosened or lost from that living chain of causes, with all the links of which, conscious or unconscious, the free-will, our only absolute Self, is coextensive and co-present. But not now dare I longer discourse of this, waiting for a loftier mood, and a nobler subject, warned from within and from without, that it is profanation to speak of these "mysteries tois maede phantasteisin, os kalon to taes dikaiosynaes kai sophrosynaes prosopon, kai oute hesperos oute eoos outo kala. To gar horon pros to horomenon syngenes kai homoion poiaesamenon dei epiballein tae thea, ou gar an popote eiden ophthalmos haelion, haelioeidaes mae gegenaemenos oude to kalon an idae psychae, mae kagae genomenae—to those to whose imagination it has never been presented, how beautiful is the countenance of justice and wisdom; and that neither the morning nor the evening star are so fair. For in order to direct the view aright, it behoves that the beholder should have made himself congenerous and similar to the object beheld. Never could the eye have beheld the sun, had not its own essence been soliform," (i.e. pre-configured to light by a similarity of essence with that of light) "neither can a soul not beautiful attain to an intuition of beauty."