Observations on Man (6th edition)/Part I/Chapter I/Section II
Section II
I took notice in the Introduction, that those ideas which resemble sensations were called ideas of sensation; and also that they might be called simple ideas, in respect of the intellectual ones which are formed from them, and of whose very essence it is to be complex. But the ideas of sensation are not entirely simple, since they must consist of parts both co-existent and successive, as the generating sensations themselves do.
Now, that the simple ideas of sensation are thus generated, agreeably to the proposition, appears, because the most vivid of these ideas are those where the corresponding sensations are most vigorously impressed, or most frequently renewed; whereas, if the sensation be faint, or uncommon, the generated idea is also faint in proportion, and, in extreme cases, evanescent and imperceptible. The exact observance of the order of place in visible ideas, and of the order of time in audible ones, may likewise serve to shew, that these ideas are copies and offsprings of the impressions made on the eye and ear, in which the same orders were observed respectively. And though it happens, that trains of visible and audible ideas are presented in sallies of the fancy, and in dreams, in which the order of time and place is different from that of any former impressions, yet the small component parts of these trains are copies of former impressions; and reasons may be given for the varieties of their compositions.
It is also to be observed, that this proposition bears a great resemblance to the third; and that, by this resemblance, they somewhat confirm and illustrate one another. According to the third proposition, sensations remain for a short time after the impression is removed; and these remaining sensations grow feebler and feebler, till they vanish. They are therefore, in some part of their declension, of about the same strength with ideas, and in their first state, are intermediate between sensations and ideas. And it seems reasonable to expect, that, if a single sensation can leave a perceptible effect, trace, or vestige, for a short time, a sufficient repetition of a sensation may leave a perceptible effect of the same kind, but of a more permanent nature, i.e. an idea, which shall recur occasionally, at long distances of time, from the impression of the corresponding sensation, and vice versâ. As to the occasions and causes, which make ideas recur, they will be considered in the next proposition but one.
The method of reasoning used in the last paragraph is farther confirmed by the following circumstance; viz. that both the diminutive declining sensations, which remain for a short space after the impressions of the objects cease, and the ideas, which are the copies of such impressions, are far more distinct and vivid, in respect of visible and audible impressions, than of any others. To which it may be added, that, after travelling, hearing music, &c. trains of vivid ideas are very apt to recur, which correspond very exactly to the late impressions, and which are of an intermediate nature between the remaining sensations of the third proposition, in their greatest vigour, and the ideas mentioned in this.
The sensations of feeling, taste and smell, can scarce be said to leave ideas, unless very indistinct and obscure ones. However, as analogy leads one to suppose that these sensations may leave traces of the same kind, though not in the same degree, as those of sight and hearing; so the readiness with which we reconnoitre sensations of feeling, taste, and smell, that have been often impressed, is an evidence that they do so; and these generated traces or dispositions of mind may be called the ideas of feeling, taste, and smell. In sleep, when all our ideas are magnified, those of feeling, taste, and smell, are often sufficiently vivid and distinct; and the same thing happens in some few cases of vigilance.
This correspondence of the diminutive vibrations to the original sensory ones, consists in this, that they agree in kind, place, and line of direction; and differ only in being more feeble, i.e. in degree.
This proposition follows from the foregoing. For since sensations, by being often repeated, beget ideas, it cannot but be that those vibrations, which accompany sensations, should beget something which may accompany ideas in like manner; and this can be nothing but feebler vibrations, agreeing with the sensory generating vibrations in kind, place, and line of direction.
Or thus: By the first proposition it appears, that some motion must be excited in the medullary substance, during each sensation; by the fourth, this motion is determined to be a vibratory one: since therefore some motion must also, by the second, be excited in the medullary substance during the presence of each idea, this motion cannot be any other than a vibratory one: else how should it proceed from the original vibration attending the sensation, in the same manner as the idea does from the sensation itself? It must also agree in kind, place, and line of direction, with the generating vibration. A vibratory motion, which recurs t times in a second, cannot beget a diminutive one that recurs ½ t, or 2 t times; nor one originally impressed on the region of the brain corresponding to the auditory nerves, beget diminutive vibrations in the region corresponding to the optic nerves; and so of the rest. The line of direction must likewise be the same in the original and derivative vibrations. It remains therefore, that each simple idea of sensation be attended by diminutive vibrations of the same kind, place, and line of direction, with the original vibrations attending the sensation itself: or, in the words of the proposition, that sensory vibrations, by being frequently repeated, beget a disposition to diminutive vibrations corresponding to themselves respectively. We may add, that the vibratory nature of the motion which attends ideas, may be inferred from the continuance of some ideas, visible ones for instance, in the fancy for a few moments.
This proof of the present proposition from the foregoing appears to be incontestable, admitting the fourth: however, it will much establish and illustrate the doctrines of vibrations and association, to deduce it directly, if we can, from the nature of vibratory motions, and of an animal body; and not only from the relation between sensations and ideas. Let us see, therefore, what progress we can make in such an attempt.
First, then, if we admit vibrations of the medullary particles at all, we must conceive, that some take place in the fœtus in utero, both on account of the warmth in which it lies, and of the pulsation of those considerable arteries, which pass through the medullary substance, and which consequently must compress and agitate it upon every contraction of the heart. And these vibrations are probably either uniform in kind and degree, if we consider short spaces of time; or, if long ones, increase in a slow uniform manner, and that in degree only, as the fœtus in utero increases in bulk and strength. They are also probably the same in all the different regions of the medullary substance. Let these vibrations be called the natural vibrations.
Secondly, As soon as the child is born, external objects act upon it violently, and excite vibrations in the medullary substance, which differ from the natural ones, and from each other, in degree, kind, place, and line of direction. We may also conceive that each region of the medullary substance has such a texture as to receive, with the greatest facility, the several specific vibrations, which the objects corresponding respectively to these regions, i.e. to their nerves, are most disposed to excite. Let these vibrations be, for the present, called preternatural ones, in contradistinction to those which we just now called natural ones.
Thirdly, Representing now the natural vibrations by N, and the preternatural ones, from various objects, by A, B, C, &c. let us suppose the first object to impress the vibrations A, and then to be removed. It is evident from the nature of vibratory motions, that the medullary substance will not, immediately upon the removal of this object, return to its natural state N, but will remain, for a short space of time, in the preternatural state A, and pass gradually from A to N. Suppose the same object to be impressed again and again, for a sufficient number of times, and it seems to follow, that the medullary substance will be longer in passing from A to N, after the second impression than after the first, after the third impression than second, &c. till, at last, it will not return to its natural original state of vibration N at all, but remain in the preternatural state A, after the vibrations have fallen to a diminutive pitch, their kind and place, or chief seat, and their line of directions, continuing the same. This state may therefore be fitly denoted by a, and, being now in the place of the natural state N, it will be kept up by the heat of the medullary substance, and the pulsation of its arteries. All this seems to follow from the above-mentioned disposition of animal bodies to accommodate themselves to, and continue in, almost any state that is often impressed; which is evident from innumerable both common and medical observations, whatever be determined concerning the manner of explaining and accounting for these facts. For the alterations which habit, custom, frequent impression, &c. make in the small constituent particles, can scarce be any thing besides alterations of the distances, and mutual actions, of these particles; and these last alterations must alter the natural tendency to vibrate. We must, however, here resume the supposition made in the last paragraph, viz. that the several regions of the brain have such a texture as disposes them to those specific vibrations, which are to be impressed by the proper objects in the events of life. And this will much facilitate and accelerate the transition of the state N into a; since we are to suppose a predisposition to the state A, or a.
It will somewhat illustrate and confirm this reasoning, to remark, that musical strings always accommodate themselves to, and lean towards the state into which they were last put. Thus the tone of a musical string either rises or falls upon altering its tension, according as the preceding tension was greater or less than its present tension. Now the small component parts of a musical string must recede from, and approach to, each other, i.e. must oscillate lengthways, during every transverse oscillation of the string. And this must arise from the mutual influences of the component particles tending to their last superinduced state. Let us suppose something analogous to this to take place in the component molecules of the brain, the molecules of the molecules, &c. and it will follow, that A may overpower N, and a become the natural state. Now, since the human body is composed of the same matter as the external world, it is reasonable to expect, that its component particles should be subjected to the same subtle laws. And the exquisite structure of animal bodies in so many other respects, makes it easier to conceive, that the organ of organs, viz. the medullary substance, should be endued with a proper subtle ultimate structure, for the purpose of retaining a state that is frequently impressed. One may guess also, that it is better suited to this purpose during its growth, i.e. in passing from infancy to adult age, than afterwards; as this would be very agreeable to the phænomena.
Fourthly, Suppose now the vibrations A, B, C, D, &c. belonging to each of the senses, to be excited, and repeated in such order and manner as usually happens to the new-born infant upon its entrance into this new scene of things. It is evident, that these will have a greater power to overrule the natural state N, than the vibrations A from one single object could have: for A affected only one region of the medullary substance primarily; whereas A, B, C, D, &c. affect all the regions primarily in their turn. It is evident also, that the secondary vibrations, or those which are propagated from the region of the medullary substance primarily affected into the rest, will be overruled, in great measure, in each region, by the primary vibrations peculiar to that region. Lastly, It is evident, that of the vibrations which are excited in each region, no one can prevail over all the rest, but each must leave an effect, in proportion to its strength and frequency. We may conceive, therefore, that each region of the medullary substance will have a tendency generated in it to vibrate with vibrations of the same frequency (but weaker in degree) as those which the several appropriated objects impress upon it respectively; and that diminutive vibrations resembling them will rise in succession in each region. For each region may easily be conceived to lean sometimes to the vibrations from one object, sometimes to those from another, according to the strength, frequency, and novelty of the impression, the then present disposition of the nervous system, association (of which in the two next propositions), and other such-like causes. And for the same reason, as in every sense the idea of some one object of that sense must prevail over all the rest, we may conclude, that sometimes the ideas belonging to one sense, sometimes those belonging to another, will prevail over the rest.
Or thus: Some vibrations there must always be in the medullary substance, on account of its heat, and the pulsation of the arteries which pass through it. These cannot be the natural ones N, because they will soon be overruled by the great force and variety of impressions made on the new-born infant, which must also dispose each region of the brain to lean to some or other of those vibrations which are excited in it primarily. Hence we may conceive, that a very complex set of vibrations, arising from the mixture and combinations of degree, kind, place, and line of direction, exists always in the medullary substance, being kept up by its heat, and the pulsation of its arteries, when other causes are wanting, almost in the same manner as in a concert of music the air is agitated by vibrations of a very complex kind. But then, as in a concert, some one instrument generally strikes the ear more than the rest, so of the complex vibrations which exist in the medullary substance, some one part will prevail over the rest, and present the corresponding idea to the mind. Some region must be disposed, at each instant, to vibrate stronger than the rest; and of the specific vibrations which are generally impressed upon this region, some one will have a more favourable concurrence of circumstances than the rest. And thus it will follow, according to the terms of the proposition, that sensory vibrations, by being sufficiently repeated, will beget a disposition to miniature vibrations corresponding to them respectively; or, using the appellations above assumed, that A, B, C, &c. will beget a, b, c, &c.
If we allow the proof of this proposition thus deduced from the nature of vibratory motions, and of an animal body, the foregoing proposition will follow from it, and hold equally, in respect of the senses of feeling, taste, and smell, as of sight and hearing. Or, in other words, if we allow that original impressed vibratory motions leave a tendency to miniature ones of the same kind, place, and line of direction, it will follow, that sensations must beget ideas, and that not only in the senses of sight and hearing, where the ideas are sufficiently vivid and distinct, but in the three others, since their sensations are also conveyed to the mind by means of vibratory motions. We may also perhaps discover hereafter, from the nature of vibratory motions, and of the human brain, compared with the circumstances of life, why the ideas of one sense are more vivid and distinct than those of another.
Sensations may be said to be associated together, when their impressions are either made precisely at the same instant of time, or in the contiguous successive instants. We may therefore distinguish association into two sorts, the synchronous, and the successive.
The influence of association over our ideas, opinions, and affections, is so great and obvious, as scarcely to have escaped the notice of any writer who has treated of these, though the word association, in the particular sense here affixed to it, was first brought into use by Mr. Locke. But all that has been delivered by the ancients and moderns, concerning the power of habit, custom, example, education, authority, party-prejudice, the manner of learning the manual and liberal arts, &c. goes upon this doctrine as its foundation, and may be considered as the detail of it, in various circumstances. I here begin with the simplest case, and shall proceed to more and more complex ones continually, till I have exhausted what has occurred to me upon this subject.
This proposition, or first and simplest case of association, is manifest from innumerable common observations. Thus, the names, smells, tastes, and tangible qualities of natural bodies, suggest their visible appearances to the fancy, i.e. excite their visible ideas; and, vice versâ, their visible appearances impressed on the eye raise up those powers of reconnoitring their names, smells, tastes, and tangible qualities, which may not improperly be called their ideas, as above noted; and in some cases raise up ideas, which may be compared with visible ones, in respect of vividness. All which is plainly owing to the association of the several sensible qualities of bodies with their names, and with each other. It is remarkable, however, as being agreeable to the superior vividness of visible and audible ideas, before taken notice of, that the suggestion of the visible appearance from the name is the most ready of any other; and, next to this, that of the name from the visible appearance; in which last case, the reality of the audible idea, when not evident to the fancy, may be inferred from the ready pronunciation of the name. For it will be shewn hereafter, that the audible idea is most commonly a previous requisite to pronunciation. Other instances of the power of association may be taken from compound visible and audible impressions. Thus the sight of part of a large building suggests the idea of the rest instantaneously; and the sound of the words which begin a familiar sentence, brings the remaining part to our memories in order, the association of the parts being synchronous in the first case, and successive in the last.
It is to be observed, that, in successive associations, the power of raising the ideas is only exerted according to the order in which the association is made. Thus, if the impressions A, B, C, be always made in the order of the alphabet, B impressed alone will not raise a, but c only. Agreeably to which it is easy to repeat familiar sentences in the order in which they always occur, but impossible to do it readily in an inverted one. The reason of this is, that the compound idea, c, b, a, corresponds to the compound sensation C, B, A; and therefore requires the impression of C, B, A, in the same manner as a, b, c, does that of A, B, C. This will, however, be more evident, when we come to consider the associations of vibratory motions, in the next proposition.
It is also to be observed, that the power of association grows feebler, as the number either of synchronous or successive impressions is increased, and does not extend, with due force, to more than a small one, in the first and simplest cases. But, in complex cases, or the associations of associations, of which the memory, in its full extent, consists, the powers of the mind, deducible from this source, will be found much greater than any person, upon his first entrance on these inquiries, could well imagine.
This proposition may be deduced from the foregoing, in the same manner as the ninth has been from the eighth.
But it seems also deducible from the nature of vibrations, and of an animal body. Let A and B be two vibrations, associated synchronically. Now, it is evident, that the vibration A (for I will, in this proposition, speak of A and B in the singular number, for the sake of greater clearness) will, by endeavouring to diffuse itself into those parts of the medullary substance which are affected primarily by the vibration B, in some measure modify and change B, so as to make B a little different from what it would be, if impressed alone. For the same reasons the vibration A will be a little affected, even in its primary seat, by the endeavour of B to diffuse itself all over the medullary substance. Suppose now the vibrations A and B to be impressed at the same instant, for a thousand times; it follows, from the ninth proposition, that they will first overcome the disposition to the natural vibrations N, and then leave a tendency to themselves, which will now occupy the place of the original natural tendency to vibrations. When therefore the vibration A is impressed alone, it cannot be entirely such as the object would excite of itself, but must lean, even in its primary seat, to the modifications and changes induced by B, during their thousand joint impressions; and therefore much more, in receding from this primary seat, will it lean that way; and when it comes to the seat of B, it will excite B’s miniature a little modified and changed by itself.
Or thus: When A is impressed alone, some vibration must take place in the primary seat of B, both on account of the heat and pulsation of the arteries, and because A will endeavour to diffuse itself over the whole medullary substance. This cannot be that part of the natural vibrations N, which belongs to this region, because it is supposed to be overruled already. It cannot be that which A impressed alone would have propagated into this region, because that has always hitherto been overruled, and converted into B; and therefore cannot have begotten a tendency to itself. It cannot be any full vivid vibration, such as B, C, D, &c. belonging to this region, because all full vibrations require the actual impression of an object upon the corresponding external organ. And of miniature vibrations belonging to this region, such as b, c, d, &c. it is evident, that b has the preference, since A leans to it a little, even in its own primary seat, more and more, in receding from this, and almost entirely, when it comes to the primary seat of B. For the same reasons B impressed alone will excite a; and, in general, if A, B, C, &c. be vibrations synchronically impressed on different regions of the medullary substance, A impressed alone will at last excite b, c, &c. according to the proposition.
If A and B be vibrations impressed successively, then will the latter part of A, viz. that part which, according to the third and fourth propositions, remains, after the impression of the object ceases, be modified and altered by B, at the same time that it will a little modify and alter it, till at last it be quite overpowered by it, and end in it. It follows therefore, by a like method of reasoning, that the successive impression of A and B, sufficiently repeated, will so alter the medullary substance, as that when A is impressed alone, its latter part shall not be such as the sole impression of A requires, but lean towards B, and end in b at last. But B will not excite a in a retrograde order; since, by supposition, the latter part of B was not modified and altered by A, but by some other vibration, such as C or D. And as B, by being followed by C, may at last raise c; so b, when raised by A, in the method here proposed, may be also sufficient to raise c; inasmuch as the miniature c being a feeble motion, not stronger, perhaps, than the natural vibrations N, requires only to have its kind, place, and line of direction, determined by association, the heat and arterial pulsation conveying to it the requisite degree of strength. And thus A impressed alone will raise b, c, &c. in successive associations, as well as in synchronous ones, according to the proposition.
It seems also, that the influence of A may, in some degree, reach through B to C; so that A of itself may have some effect to raise c, as well as by means of b. However, it is evident, that this chain must break off, at last, in long successions; and that sooner or later, according to the number and vigour of the repeated impressions. The power of miniature vibrations to raise other miniatures may, perhaps, be made clearer to mathematicians, by hinting, that the efficacy of any vibration to raise any other, is not in the simple ratio of its vividness, but as some power thereof less than unity; for thus b may raise c, a weaker vibration than b, c may raise d, &c. with more facility than if the efficacy was in the simple ratio of the vividness, and yet so that the series shall break off at last.
If the ninth proposition be allowed, we may prove this in somewhat a shorter and easier manner, as follows. Since the vibrations A and B are impressed together, they must, from the diffusion necessary to vibratory motions, run into one vibration; and consequently, after a number of impressions sufficiently repeated, will leave a trace, or miniature, of themselves, as one vibration, which will recur every now and then, from slight causes. Much rather, therefore, may the part b of the compound miniature a + b recur, when the part A of the compound original vibration A + B is impressed.
And as the ninth proposition may be thus made to prove the present, so it ought to be acknowledged and remarked here, that unless the ninth be allowed, the present cannot be proved, or that the power of association is founded upon, and necessarily requires, the previous power of forming ideas, and miniature vibrations. For ideas, and miniature vibrations, must first be generated, according to the eighth and ninth propositions, before they can be associated, according to the tenth and this eleventh. But then (which is very remarkable) this power of forming ideas, and their corresponding miniature vibrations, does equally presuppose the power of association. For since all sensations and vibrations are infinitely divisible, in respect of time and place, they could not leave any traces or images of themselves, i.e. any ideas, or miniature vibrations, unless their infinitesimal parts did cohere together through joint impression, i.e. association. Thus, to mention a gross instance, we could have no proper idea of a horse, unless the particular ideas of the head, neck, body, legs, and tail, peculiar to this animal, stuck to each other in the fancy, from frequent joint impression. And, therefore, in dreams, where complex associations are much weakened, and various parcels of visible ideas, not joined in nature, start up together in the fancy, contiguous to each other, we often see monsters, chimeras, and combinations, which have never been actually presented.
Association seems also necessary to dispose the medullary substance to this or that miniature vibration, in succession, after the miniatures of a large number of original vibrations have been generated.
Nor does there seem to be any precise limit which can be set to this mutual dependence of the powers of generating miniatures, and of association upon each other: however they may both take place together, as the heart and brain are supposed to do, or both depend upon one simple principle; for it seems impossible, that they should imply one another ad infinitum. There is no greater difficulty here than in many other cases of mutual indefinite implication, known and allowed by all. Nay, one may almost deduce some presumption in favour of the hypothesis here produced, from this mutual indefinite implication of its parts so agreeable to the tenor of nature in other things. And it is certainly a presumption in its favour, that a less power of generating miniatures will be a foundation for a larger of association, and vice versâ, till, at last, the whole superstructure of ideas and associations observable in human life may, by proceeding upwards according to analysis, and downwards according to synthesis, be built upon as small a foundation as we please. Thus we may observe, that neither does this eleventh proposition necessarily require the ninth, in its full extent, not vice versâ, for their demonstration. The least miniatures, with the feeblest cohesions of their parts, will, by degrees, run into larger, with stronger cohesions, from the same principles; nor are there any visible limits to the influence and extent of these powers, supposing the natural faculties of the being under consideration sufficiently extended.
Let me add, that the generation of sensible ideas from sensations, and the power of raising them from association, when considered as faculties of the mind, are evident and unquestionable. Since therefore sensations are conveyed to the mind, by the efficiency of corporeal causes of the medullary substance, as is acknowledged by all physiologists and physicians, it seems to me, that the powers of generating ideas, and raising them by association, must also arise from corporeal causes, and consequently admit of an explication from the subtle influences of the small parts of matter upon each other, as soon as these are sufficiently understood; which is farther evinced from the manifest influences of material causes upon our ideas and associations, taken notice of under the second proposition. And as a vibratory motion is more suitable to the nature of sensation than any other species of motion, so does it seem also more suitable to the powers of generating ideas, and raising them by association. However, these powers are evident independently, as just now observed; so that the doctrine of association may be laid down as a certain foundation, and a clew to direct our future inquiries, whatever becomes of that of vibrations.
In order to explain and prove this proposition, it will be requisite to give some previous account of the manner in which simple ideas of sensation may be associated together.
Case 1. Let the sensation A be often associated with each of the sensations B, C, D, &c. i.e. at certain times with B, at certain other times with C, &c. it is evident, from the tenth proposition, that A, impressed alone, will, at last, raise b, c, d, &c. all together, i.e. associate them with one another, provided they belong to different regions of the medullary substance; for if any two, or more, belong to the same region, since they cannot exist together in their distinct forms, A will raise something intermediate between them.
Case 2. If the sensations A, B, C, D, &c. be associated together, according to various combinations of twos, or even threes, fours, &c. then will A raise b, c, d, &c. also B raise a, c, d, &c. as in case the first.
It may happen, indeed, in both cases, that A may raise a particular miniature, as b, preferably to any of the rest, from its being more associated with B, from the novelty of the impression of B, from a tendency in the medullary substance to favour b, &c. and in like manner, that b may raise c or d preferably to the rest. However, all this will be over-ruled, at last, by the recurrency of the associations; so that any one of the sensations will excite the ideas of the rest at the same instant, i.e. associate them together.
Case 3. Let A, B, C, D, &c. represent successive impressions, it follows from the tenth and eleventh propositions, that A will raise b, c, d, &c. B raise c, d, &c. And though the ideas do not, in this case, rise precisely at the same instant, yet they come nearer together than the sensations themselves did in their original impression; so that these ideas are associated almost synchronically at last, and successively from the first. The ideas come nearer to one another than the sensations, on account of their diminutive nature, by which all that appertains to them is contracted. And this seems to be as agreeable to observation as to theory.
Case 4. All compound impressions A + B + C + D, &c. after sufficient repetition leave compound miniatures a + b + c + d, &c. which recur every now and then from slight causes, as well such as depend on association, as some which are different from it. Now, in these recurrences of compound miniatures, the parts are farther associated, and approach perpetually nearer to each other, agreeably to what was just now observed; i.e. the association becomes perpetually more close and intimate.
Case 5. When the ideas a, b, c, d, &c. have been sufficiently associated in any one or more of the foregoing ways, if we suppose any single idea of these, a for instance, to be raised by the tendency of the medullary substance that way, by the association of A with a foreign sensation or idea X or x, &c. this idea a, thus raised, will frequently bring in all the rest, b, c, d, &c. and so associate all of them together still farther.
And upon the whole, it may appear to the reader, that the simple ideas of sensation must run into clusters and combinations, by association; and that each of these will, at last, coalesce into one complex idea, by the approach and commixture of the several compounding parts.
It appears also from observation, that many of our intellectual ideas, such as those that belong to the heads of beauty, honour, moral qualities, &c. are, in fact, thus composed of parts, which, by degrees, coalesce into one complex idea.
And as this coalescence of simple ideas into complex ones is thus evinced, both by the foregoing theory, and by observation, so it may be illustrated, and farther confirmed, by the similar coalescence of letters into syllables and words, in which association is likewise a chief instrument. I shall mention some of the most remarkable particulars, relating to this coalescence of simple ideas into complex ones, in the following corollaries.
Cor. I. If the number of simple ideas which compose the complex one be very great, it may happen, that the complex idea shall not appear to bear any relation to these its compounding parts, nor to the external senses upon which the original sensations, which gave birth to the compounding ideas, were impressed. The reason of this is, that each single idea is overpowered by the sum of all the rest, as soon as they are all intimately united together. Thus in very compound medicines the several tastes and flavours of the separate ingredients are lost and overpowered by the complex one of the whole mass: so that this has a taste and flavour of its own, which appears to be simple and original, and like that of a natural body. Thus also, white is vulgarly thought to be the simplest and most uncompounded of all colours, while yet it really arises from a certain proportion of the seven primary colours, with their several shades or degrees. And to resume the illustration above-mentioned, taken from language, it does not at all appear to persons ignorant of the arts of reading and writing, that the great variety of complex words of languages can be analysed up to a few simple sounds.
Cor. II. One may hope, therefore, that, by pursuing and perfecting the doctrine of association, we may some time or other be enabled to analyse all that vast variety of complex ideas, which pass under the name of ideas of reflection, and intellectual ideas, into their simple compounding parts, i.e. into the simple ideas of sensation, of which they consist. This would be greatly analogous to the arts of writing, and resolving the colour of the sun’s light, or natural bodies, into their primary constituent ones. The complex ideas which I here speak of, are generally excited by words, or visible objects; but they are also connected with other external impressions, and depend upon them, as upon symbols. In whatever way we consider them, the trains of them which are presented to the mind seem to depend upon the then present state of the body, the external impressions, and the remaining influence of prior impressions and associations taken together.
Cor. III. It would afford great light and clearness to the art of logic, thus to determine the precise nature and composition of the ideas affixed to those words which have complex ideas, in a proper sense, i.e. which excite any combinations of simple ideas united intimately by association; also to explain, upon this foundation, the proper use of those words, which have no ideas. For there are many words which are mere substitutes for other words, and many which are only auxiliaries. Now it cannot be said, that either of these have ideas, properly so called. And though it may seem an infinite and impossible task, thus to analyse the significations and uses of words, yet, I suppose, this would not be more difficult, with the present philological and philosophical helps to such a work, than the first making of dictionaries and grammars, in the infancy of philology. Perhaps it may not be amiss just to hint, in this place, that the four following classes comprise all the possible kinds into which words can be distinguished, agreeably to the plan here proposed:
1. Words which have ideas, but no definitions.
2. Words which have both ideas and definitions.
3. Words which have definitions, but no ideas.
4. Words which have neither ideas nor definitions.
It is quite manifest, that words seen or heard, can raise no ideas in the mind, or vibrations in the brain, distinct from their visible and audible impressions, except as far as they get new powers from associations, either incidental ones or arising from express design, as in definitions; and therefore, that all other ways of considering words, besides what is here suggested, are either false or imperfect.
Cor. IV. As simple ideas run into complex ones by association, so complex ideas run into decomplex ones by the same. But here the varieties of the associations, which increase with the complexity, hinder particular ones from being so close and permanent, between the complex parts of decomplex ideas, as between the simple parts of complex ones: to which it is analogous, in languages, that the letters of words adhere closer together than the words of sentences, both in writing and speaking.
Cor. V. The simple ideas of sensation are not all equally and uniformly concerned in forming complex and decomplex ideas; i.e. these do not result from all the possible combinations of twos, threes, fours, &c. of all the simple ideas; but, on the contrary, some simple ideas occur in the complex and decomplex ones much oftener than others; and the same holds of particular combinations by twos, threes, &c. and innumerable combinations never occur at all in real life, and, consequently, are never associated into complex or decomplex ideas. All which corresponds to what happens in real languages; some letters, and combinations of letters, occur much more frequently than others, and some combinations never occur at all.
Cor. VI. As persons who speak the same language have, however, a different use and extent of words, so, though mankind, in all ages and nations, agree, in general, in their complex and decomplex ideas, yet there are many particular differences in them; and these differences are greater or less, according to the difference, or resemblance, in age, constitution, education, profession, country, age of the world, &c. i.e. in their impressions and associations.
Cor. VII. When a variety of ideas are associated together, the visible idea, being more glaring and distinct than the rest, performs the office of a symbol to all the rest, suggests them, and connects them together. In this it somewhat resembles the first letter of a word, or first word of a sentence, which are often made use of to bring all the rest to mind.
Cor. VIII. When objects and ideas, with their most common combinations, have been often presented to the mind, a train of them, of a considerable length, may, by once occurring, leave such a trace, as to recur in imagination, and in miniature, in nearly the same order and proportion as in this single occurrence. For, since each of the particular impressions and ideas is familiar, there will want little more for their recurrency, than a few connecting links; and even these may be, in some measure, supplied by former similar instances. These considerations, when duly unfolded, seem to me sufficient to explain the chief phænomena of memory; and it will be easily seen from them, that the memory of adults, and masters in any science, ought to be much more ready and certain than that of children and novices, as it is found to be in fact.
Cor. IX. When the pleasure or pain attending any sensations and ideas is great, all the associations belonging to them are much accelerated and strengthened. For the violent vibrations excited in such cases, soon overrule the natural vibrations, and leave in the brain a strong tendency to themselves, from a few impressions. The associations will therefore be cemented sooner and stronger than in common cases; which is found agreeable to the fact.
Cor. X. As many words have complex ideas annexed to them, so sentences, which are collections of words, have collections of complex ideas, i.e. have decomplex ideas. And it happens, in most cases, that the decomplex idea belonging to any sentence is not compounded merely of the complex ideas belonging to the words of it; but that there are also many variations, some oppositions, and numberless additions. Thus, propositions, in particular, excite, as soon as heard, assent or dissent; which assent and dissent consist chiefly of additional complex ideas, not included in the terms of the proposition. And it would be of the greatest use, both in the sciences and in common life, thoroughly to analyse the matter, to shew in what manner, and by what steps, i.e. by what impressions and associations, our assent and dissent, both in scientifical and moral subjects, is formed.
This proposition is analogous to the ninth and eleventh, and may be deduced from the last, as they are from the eighth and tenth respectively. It is also an evidence and illustration of the second; shewing, not only that the state of the medullary substance is changed, according to the several natures of the ideas which are presented to the mind; but also shewing, in general, of what kind this change is, and in what manner it is effected.
For these complex vibrations may consist of so many parts co-existent and successive, and these parts may so alter and exalt one another, as that the resulting agitations in the medullary substance may no longer be miniature vibrations, but vivid ones equal to those excited by objects impressed on the senses. This process may be farther favoured by a mixture of vivid real impressions among the ideas, by the irritability of the medullary substance, by a previous disposition to the vibrations to be excited, &c.
Cor. I. When the complex miniature vibrations are thus exalted in degree, we are to conceive, that the corresponding complex ideas are proportionally exalted, and so pass into intellectual affections and passions. We are therefore to deduce the origin of the intellectual pleasures and pains, which are the objects of these affections and passions, from the source here laid open.
Cor. II. Since the present proposition unfolds the nature of affections and will, in the same manner, and from the same principles, as the twelfth does that of ideas, intellect, memory, and fancy; it follows, that all these are of the same original and consideration, and differ only in degree, or some accidental circumstances. They are all deducible from the external impressions made upon the senses, the vestiges or ideas of these, and their mutual connexions by means of association, taken together and operating on one another.
Cor. III. It follows also from this proposition, that the intellectual pleasures and pains may be greater, equal, or less, than the sensible ones, according as each person unites more or fewer, more vivid or more languid, miniature vibrations in the formation of his intellectual pleasures and pains, &c.
Cor. IV. It is evident, that all the vibrations which belong to ideas, and intellectual affections, must reside in the brain, or even in the most internal parts of it, not in the spinal marrow or nerves. The brain is therefore the seat of the rational soul, i.e. of the soul, as far as it is influenced by reasons and moral motives, even though we should admit, that the spinal marrow and nerves, are, in part, the sensorium, or the seat of the sensitive soul; which is some argument, that this ought not to be admitted, but that the sensorium, in men at least, ought to be placed in the internal parts of the brain.
Cor. V. It is of the utmost consequence to morality and religion, that the affections and passions should be analysed into their simple compounding parts, by reversing the steps of the associations which concur to form them. For thus we may learn how to cherish and improve good ones, check and root out such as are mischievous and immoral, and how suit our manner of life, in some tolerable measure, to our intellectual and religious wants. And as this holds, in respect of persons of all ages, so it is particularly true, and worthy of consideration, in respect of children and youth. The world is, indeed, sufficiently stocked with general precepts for this purpose, grounded on experience; and whosoever will follow these faithfully, may expect good general success. However, the doctrine of association, when traced up to the first rudiments of understanding and affection, unfolds such a scene as cannot fail both to instruct and alarm all such as have any degree of interested concern for themselves, or of a benevolent one for others. It ought to be added here, that the doctrine of association explains also the rise and progress of those voluntary and semi-voluntary powers, which we exert over our ideas, affections, and bodily motions (as I shall shew hereafter, Prop. XXI.) and by doing this, teaches us how to regulate and improve these powers.
Cor. VI. If beings of the same nature, but whose affections and passions are, at present, in different proportions to each other, be exposed for an indefinite time to the same impressions and associations, all their particular differences will, at last, be overruled, and they will become perfectly similar, or even equal. They may also be made perfectly similar, in a finite time, by a proper adjustment of the impressions and associations.
Cor. VII. Our original bodily make, and the impressions and associations which affect us in passing through life, are so much alike, and yet not the same, that there must be both a great general resemblance amongst mankind, in respect to their intellectual affections, and also many particular differences.
Cor. VIII. Some degree of spirituality is the necessary consequence of passing through life. The sensible pleasures and pains must be transferred by association more and more every day, upon things that afford neither sensible pleasure nor sensible pain in themselves, and so beget the intellectual pleasures and pains.
Cor. IX. Let the letters a, b, c, d, e, &c. represent the sensible pleasures; x, y, and z, the sensible pains, supposed to be only three in number; and let us suppose all these, both pleasures and pains, to be equal to one another: If now the ideas of these sensible pleasures and pains be associated together, according to all the possible varieties, in order to form intellectual pleasures and pains, it is plain, that pleasure must prevail in all the combinations of seven or more letters; and also, that when the several parts of these complex pleasures are sufficiently united by association, the pains which enter their composition will no longer be distinguished separately, but the resulting mixed and complex pleasures appear to be pure and simple ones, equal in quantity to the excess of pleasure above pain, in each combination. Thus association would convert a state in which pleasure and pain were both perceived by turns, into one in which pure pleasure alone would be perceived; at least, would cause the beings who were under its influence to an indefinite degree, to approach to this last state nearer than by any definite difference. Or, in other words, association, under the supposition of this corollary, has a tendency to reduce the state of those who have eaten of the tree of the knowledge of good and evil, back again to a paradisiacal one. Now, though the circumstances of mankind are not the same with those supposed in this corollary, yet they bear a remarkable resemblance thereto, during that part of our existence which is exposed to our observation. For our sensible pleasures are far more numerous than our sensible pains; and though the pains be, in general, greater than the pleasures, yet the sum total of these seems to be greater than that of those; whence the remainder, after the destruction of the pains by the opposite and equal pleasures, will be pure pleasure.
Cor. X. The intellectual pleasures and pains are as real as the sensible ones, being, as we have seen, nothing but the sensible ones variously mixed and compounded together. The intellectual pleasures and pains are also all equally of a factitious and acquired nature. We must therefore estimate all our pleasures equally, by their magnitude, permanency, and tendency to procure others; and our pains in like manner.
Cor. XI. The sensible pleasures and pains have a greater tendency to destroy the body, than the intellectual ones; for they are of a particular local nature, and so bear hard upon the organs which convey them. But the destruction of any one considerable part of the body is the destruction of the whole, from the sympathy of the parts; whereas the intellectual pleasures and pains, being collected from all quarters, do not much injure any organ particularly, but rather bring on an equable gradual decay of the whole medullary substance, and all the parts thereon depending.
Cor. XII. This proposition, and its corollaries, afford some pleasing presumptions; such are, that we have a power of suiting our frame of mind to our circumstances, of correcting what is amiss, and improving what is right: that our ultimate happiness appears to be of a spiritual, not corporeal nature; and therefore that death, or the shaking off the gross body, may not stop our progress, but rather render us more expedite in the pursuit of our true end: that association tends to make us all ultimately similar; so that if one be happy, all must: and lastly, that the same association may also be shewn to contribute to introduce pure ultimate spiritual happiness, in all, by a direct argument, as well as by the just-mentioned indirect one.