Lectures on the Philosophy of the Human Mind (Vol. 1 of 3)

These arguments, however, though they seem to me to invalidate completely the only arguments which I can imagine to be urged in support of our original perception of figure by the eye, are negative only. But there is also a positive argument, which seems to me truly decisive, against the supposed necessary perception of visible figure, – that it implies the blending of things which cannot be blended. If the mere visual sensation of colour imply, in itself, no figure, I can conceive it to be blended with any figure; but not so, if it imply, in itself, a fixed definite figure, so essential to the very sensation of the colour, that without it the colour could not for a single moment be perceived. During the whole time, then, in which I am gazing on a wide landscape, there is, according to the opinion of those who contend for the necessary perception of visible figure, not colour merely, but a certain small coloured expanse, of definite outline, constantly perceived – since, without this, colour itself could not be perceived; and, during all this time, there is also a notion of a figure of a very different kind, of three dimensions, and of magnitude almost infinitely greater, combined, not with colour merely, but with the same coloured expanse. There must, therefore, be some possible combination of these forms and magnitudes; since it is the colour which we perceive that is blended with the tangible magnitudes suggested. Now, though there are certain feelings which may coexist and unite, it appears to me, that there are others which cannot be so blended. I may combine, for example, my notion of a plane or convex surface, with my notion of whiteness or blueness, hardness or softness, roughness or smoothness; but I cannot blend my notions of these two surfaces, the plane and the convex, as one surface, both plane and convex, more than I can think of a whole which is less than a fraction of itself, or a square, of which the sides are not equal, and the angles equal only to three right angles. The same blue or white surface cannot appear to me, then, at once plane and convex, as it must do if there be a visible figure of one exact outline coexisting with the tactual figure which is of a different outline; nor, even though the surface were in both cases plane, can it appear to me, at the same moment, half an inch square, and many feet square. All this must be done, however, as often as we open our eyes, if there be truly any perception of visible figure coexisting with the mere suggestions of touch. The visible figure of the sphere, on which I fix my gaze, is said to be a plane of two dimensions inseparable from colour, and this inseparable colour must yet be combined with the sphere, which I perceive distinctly to be convex. According to the common theory, therefore, it is at once, to my perception, convex and plane; and, if the sphere be a large one, it is perceived, at the same moment, to be a sphere of many feet in diameter, and a plane circular surface of the diameter of a quarter of an inch. The assertion of so strange a combination of incongruities would, indeed, require some powerful arguments to justify it; yet is has been asserted, not merely without positive evidence, as if not standing in need of any proof, but in absolute opposition to our consciousness; and the only arguments which we can ever imagine to be urged for it, are, as we have seen, of no weight, – or would tend as much to prove the original visual perception of tangible figures, as of the figure that is termed visible.

Is it not at least more probable, therefore, that though, like the particles of odour when they act upon our nostrils, the rays of light affect a portion of the retina, so as to produce on it an image, which, if the eye were separated from its orbit, and its coats dissected, might be a distinct visible figure to the eye of another observer; this figure of the portion of the retina affected, enters as little into the simple original sensation of sight, as the figure of the portion of the olfactory nervous expanse, when it is affected, enters into the sensations of smell? – and that, when the simple affection of sight is blended with the ideas of suggestion, in what are termed the acquired perceptions of vision, – as, for example, in the perception of a sphere, – it is colour only which is blended with the large convexity, and not a small coloured plane? – which small coloured plane being necessarily limited in extent and form, so as never to be larger than the retina itself, cannot blend with various forms and magnitudes, and which, if it could even be supposed to constitute a part of the convexity of a sphere perceived by us, still could not diffuse its own limited and inseparable colour over the whole magnitude of the sphere.

I have stated to you my own opinion with respect to visible figure, – an opinion, which to myself, I confess, appears almost certain, or, at least, far more probable than the opinion generally entertained, that has no evidence in our consciousness at any one moment of vision to support it. But on subjects of this kind, which are in themselves so very subtile, and, therefore, so liable to error, I must beg you, at all times, and especially when the opposite sentiment has the authority of general belief, to consider any opinion, which I may submit to you, as offered more to your reflection, than for your passive adoption of it. If I wish you, – reverently, indeed, but still freely, – to weigh the evidence of doctrines of philosophy, which are sanctioned even by the greatest names of every age, I must wish you still more, because it will be still more your duty, to weigh well the evidence of opinions that come to you, with no other authority than that of one very fallible individual.

In looking back on the senses which we have been considering, what a boundless field do we seem already to have been endeavouring to traverse? and how admirable would the mind have been, even though it had been capable of no other office than that of representing, in the union of all its sensations, as in a living mirror of the universe, the splendid conceptions of the great Being who formed it; or, rather of creating a-new in itself, that very universe which it represents and admires?

Such is the power of the senses; – of

– “senses, that inherit earth and heavens,Enjoy the various riches Nature yields; —Far nobler, give the riches they enjoy;Give taste to fruits, and harmony to groves,Their radiant beams to gold, and gold's bright fire;Take in at once the landscape of the world,At a small inlet, which a grain might close,And half create the wonderous world they see.But for the magic organ's powerful charm,Earth were a rude, uncoloured chaos still; —Like Milton's Eve, when gazing on the lake,Man makes the matchless image, man admires.”125

LECTURE XXX

HISTORY OF OPINIONS REGARDING PERCEPTION

Gentlemen, in my last Lecture, I brought to a conclusion my remarks on Vision, with an inquiry into the justness of the universal belief, that, in the perception of objects by this sense, there are two modifications of extension, a visible as well as a tangible figure; the one originally and immediately perceived by the eye, the other suggested by former experience. I stated, at considerable length, some arguments which induce me to believe, in opposition to the universal doctrine, – that, in what are termed the acquired perceptions of sight, there is not this union of two separate figures of different dimensions, which cannot be combined with each other, more than the mathematical conceptions of a square and a circle can be combined in the conception of one simple figure; that the original sensations of colour, though, like the sensations of smell or taste, and every other species of sensation, arising from affections of definite portions of nervous substance, do not involve the perception of this definite outline, more than mere fragrance or sweetness, but that the colour is perceived by us as figured, only in consequence of being blended by intimate associations with the feelings commonly ascribed to touch. Philosophers, indeed, have admitted, or, at least, must admit, that we have no consciousness of that which they yet suppose to be constantly taking place, and that the only figure which does truly seem to us, in vision, to be combined with colour, is that which they term tangible, – that, for example, we cannot look at a coloured sphere, of four feet diameter, without perceiving a coloured figure, which is that of a sphere four feet in diameter, and not a plain circular surface of the diameter of half an inch; yet, though we have no consciousness of perceiving any such small coloured circle, and have no reason to believe that such a perception takes place, they still contend, without any evidence whatever, that we see at every moment what we do not remember to have ever seen.

After our very full discussion of the general phenomena of perception, – as common to all our senses, and as peculiarly modified in the different tribes of our sensations, – I might now quit a subject, to which its primary interest as the origin of our knowledge, has led me to pay, perhaps, a disproportionate attention. But besides the theories, to the consideration of which our general inquiry has incidentally led us, there are some hypothetical opinions on the subject, of which it is necessary that you should know at least the outline, – not because they throw any real light on the phenomena of perception, but because, extravagantly hypothetical as they are, they are yet the opinions of philosophers, whose eminence, in other respects, renders indispensable some slight knowledge even of their very errors.

In reviewing these hypotheses, it will be necessary to call your attention to that doctrine of causation, which I before illustrated at great length, and which I trust, therefore, I may safely take for granted that you have not forgotten.

In sensation, I consider the feeling of the mind to be the simple effect of the presence of the object; or, at least, of some change, which the presence of the object produces in the sensorial organ. The object has the power of affecting the mind; the mind is susceptible of being affected by the object, – that is to say, when the organ, in consequence of the presence of the external object, exists in a certain state, the affection of the mind immediately follows. If the object were absent, in any particular case, the mind would not exist in the state which constitutes the sensation produced by it; and, if the susceptibility of the mind had been different, the object might have existed, as now, without any subsequent sensation. In all this series of mere changes, or affections, in consequence of certain other preceding changes, or affections, though a part of the series be material, and another part mental, there is truly, as I have repeatedly remarked to you, no more mystery than in any other series of changes, in which the series is not in matter and mind successively, but exclusively in one or the other. There is a change of state of one substance, in consequence of a change of some sort in another substance; and this mere sequence of change after change is all which we know in either case. The same Almighty Being, who formed the various substances to which we give the name of matter, formed also the substance to which we give the name of mind; and the qualities with which he endowed them, for those gracious ends which he intended them to answer, are mere susceptibilities of change, by which, in certain circumstances, they begin immediately to exist in different states. The weight of a body is its tendency to other bodies, varying according to the masses and distances; – in this instance, the quality may be said to be strictly material. The greenness or redness ascribed to certain rays of light, are words expressive merely of changes that arise in the mind when these rays are present on the retina; in this case, the quality, though ascribed to the material rays as antecedent, involves the consideration of a certain change of state in the mind which they affect. But the greenness or redness, though involving the consideration both of mind affected, and matter affecting, is not less conceivable by us as a quality of matter than the weight, which also involves the consideration of two substances, affecting and affected, though both go under the name of matter alone. All the sequences of phenomena are mysterious, or none are so.

It is wonderful, that the presence of a loadstone should cause a piece of iron to approach it; and that the presence of the moon, in different parts of the heavens, should be continually altering the relative tendencies of all the particles of our earth. In like manner, it is, indeed, wonderful, that a state of our bodily organs should be followed by a change of state of the mind, or a state of our mind by a change of state of our bodily organs; but it is not more wonderful, than that matter should act on distant matter, or that one affection of the mind, should be followed by another affection of the mind, since all which we know in either case, when matter acts upon matter, or when it acts upon mind, is, that a certain change of one substance has followed a certain change of another substance, – a change which, in all circumstances exactly similar, it is expected by us to follow again. We have experience of this sequence of changes alike in both cases; and, but for experience, we could not, in either case, have predicted it.

This view of causation, however, – as not more unintelligible in the reciprocal sequences of events in matter and mind than in their separate sequences, – could not occur to philosophers while they retained their mysterious belief of secret links, connecting every observed antecedent with its observed consequent; since mind and matter seemed, by their very nature, unsusceptible of any such common bondage. A peculiar difficulty, therefore, as you may well suppose, was felt, in the endeavour to account for their mutual successions of phenomena, which vanishes, when the necessity of any connecting links in causation is shewn to be falsely assumed.

In their views of perception, therefore, as a mental effect produced by a material cause, philosophers appear to have been embarrassed by two great difficulties: – the production of this effect by remote objects, – as when we look at the sun and stars, in their almost inconceivable distances above our heads; and the production of this effect by a substance, which has no common property that renders it capable of being linked with the mind in the manner supposed to be necessary for causation. These two supposed difficulties appear, to me, to have led to all the wild hypotheses that have been advanced with respect to perception.

The former of these difficulties, – in the remoteness of the object perceived, – even though the principle had not been false which supposes, that a change cannot take place in any substance, in consequence of the change of position of a distant object, – a principle, which the gravitation of every atom disproves, – arose, it is evident, from false views of the real objects of perception. It is on this account, that I was at some pains, when we entered on our inquiry into the nature of perception, to shew the futility of the distinction which is made of objects that act immediately on the senses, and those which act on them through a medium, – the medium, in this case, as light in vision, and the vibrating air in sound, being the real object of the particular sense, – and the reference to a more remote object being the result, not of the simple original sensation, but of knowledge previously acquired.

The mistake as to the real object of perception, and the supposed difficulty of action at a distance, must have had very considerable influence in producing the Peripatetic doctrine of perception by species, of which the cumbrous machinery seems to have been little more than a contrivance for destroying, as it were, the distance between the senses and the objects that were supposed to act on them. According to this doctrine, every object is continually throwing off certain shadowy films or resemblances of itself, which may be directly present to our organs of sense, at whatever distance the objects may be, from which they flowed. These species or phantasms, – the belief of the separate existence of which must have been greatly favoured by another tenet of the same school, with respect to form as essentially distinct from the matter with which it is united, were supposed to be transmitted, in a manner, which there was no great anxiety to explain, to the brain and to the mind itself. I need not detail to you the process by which these sensible species, through the intervention of what were termed the active and passive intellect, were said to become, at last, intelligible species, so as to be objects of our understanding. It is with the mere sensitive part of the process, that we have at present any concern; and in this, of itself, there is sufficient absurdity, without tracing all the further modifications, of which the absurdity is capable, if I may speak so lightly of follies that have a name, which, for more than a thousand years, was the most venerable of human names, to pass them current as wisdom, – and which were read and honoured as wisdom by the wise of so many generations.

I cannot pay you so very poor a compliment, as to suppose it necessary to employ a single moment of your time in confuting what is not only a mere hypothesis, (and an hypothesis which leaves all the real difficulties of perception precisely as before,) but which, even as an hypothesis, is absolutely inconceivable. If vision had been our only sense, we might, perhaps, have understood, at least, what was meant by the species, that directly produce our visual images. But what is the phantasm of a sound or an odour? or what species is it, which, at one moment, produces only the feeling of cold, or hardness, or figure, when a knife is pressed against us, and the next moment, when it penetrates the skin, the pain of a cut? The knife itself is exactly the same unaltered knife, when it is merely pressed against the hand, and when it produces the incision; and the difference, therefore, in the two cases, must arise, not from any species which it is constantly throwing off, since these would be the same, at every moment, but from some state of difference in the mere nerves affected.

I fear, however, that I have already fallen into the folly which I professed to avoid, – the folly of attempting to confute, what, considered in itself, is not worthy of being seriously confuted, and scarcely worthy even of being proved to be ridiculous. It must be remembered, however, in justice to its author, that the doctrine of perception, by intermediate phantasms, is not a single opinion alone, but a part of a system of opinions, and that there are many errors, which, if considered singly, appear too extravagant for the assent of any rational mind, that lose much of this extravagance, by combination with other errors, as extravagant. Whatever difficulties the hypothesis of species involved, it at least seemed to remove the supposed difficulty of perception at a distance, and by the half spiritual tenuity of the sensible images, seemed also to afford a sort of intermediate link, for the connexion of matter with mind; thus appearing to obviate, or at least to lessen, the two great difficulties, which I suppose to have given occasion to the principal hypothesis on this subject.

When the doctrine of species, as modified, in the dark and barren age of Dialectics, by all the additional absurdities, which the industrious sagacity of the schoolmen could give to it, had, at length, lost that empire, which it never should have possessed, the original difficulty of accounting for perception, remained as before. If the cause was to be linked, in some manner or other, with its effect, how was matter, so different in all its properties, to be connected with mind?

The shortest possible mode of obviating this difficulty, was, by denying that any direct causation whatever took place between our mind and our bodily organs? and hence arose the system of occasional causes, as maintained by the most distinguished of the followers of Des Cartes, – a system, which supposed, that there is no direct agency of our mind on matter, or of matter on our mind, – that we are as little capable of moving our own limbs by our volition, as of moving, by our volition, the limbs of any other person, – as little capable of perceiving the rays of light, that have entered our own eyes, as the rays which have fallen on any other eyes, – that our perception or voluntary movement is, therefore, to be referred, in every case, to the immediate agency of the Deity, the presence of rays of light, within our eye, being the mere occasion on which the Deity himself affects our mind with vision, as our desire of moving our limbs is the mere occasion, on which the Deity himself puts our limbs in motion.

It is of so much importance to have a full conviction of the dependence of all events on the great Source of Being, that it is necessary to strip the doctrine, as much as possible, of every thing truly objectionable, lest, in abandoning what is objectionable, we should be tempted to abandon also the important truth associated with it. The power of God is so magnificent in itself, that it is only when we attempt to add to it in our conception, that we run some risk of degrading what it must always be impossible for us to elevate.

That the changes which take place, whether in mind or in matter, are all, ultimately, resolvable into the will of the Deity, who formed alike the spiritual and material system of the universe, making the earth a habitation worthy of its noble inhabitant, – and man an inhabitant almost worthy of that scene of divine magnificence, in which he is placed, is a truth, as convincing to our reason, as it is delightful to our devotion. What confidence do we feel, in our joy, at the thought of the Eternal Being, from whom it flows, as if the very thought gave at once security and sanctity to our delight; and how consolotary, in our little hour of suffering, to think of Him who wills our happiness, and who knows how to produce it, even from sorrow itself, by that power which called light from the original darkness, and still seems to call, out of a similar gloom, the sunshine of every morning. Every joy thus becomes gratitude, – every sorrow resignation. The eye which looks to Heaven seems, when it turns again to the scenes of earth, to bring down with it a purer radiance, like the very beaming of the presence of the Divinity, which it sheds on every object on which it gazes, – a light

“That gilds all formsTerrestrial, in the vast, and the minute;The unambiguous footsteps of the God,Who gives its lustre to an insect's wing,And wheels His throne upon the rolling worlds.”126

That the Deity, in this sense, as the Creator of the world, and willer of all those great ends, which the laws of the universe accomplish, – is the author of the physical changes which take place in it, is then most true, – as it is most true also, that the same Power, who gave the universe its laws, can, for the particular purposes of his providence, vary these at pleasure. But there is no reason to suppose, that the objects which he has made surely for some ends, have, as made by him, no efficacy, no power of being instrumental, to his own great purpose, merely because whatever power they can be supposed to have, must have been derived from the Fountain of all power. It is, indeed, only as possessing this power, that we know them to exist; and their powers, which the doctrine of occasional causes would destroy altogether, are, relatively to us, their whole existence. It is by affecting us that they are known to us. Such is the nature of the mind, and of light, for example, that light cannot be present, or, at least, the sensorial organ cannot exist in a certain state, in consequence of its presence, without that instant affection of mind, which constitutes vision. If light have not this power of affecting us with sensation, it is, with respect to us, nothing, – for we know it only as the cause of the visual affection. That which excites in us the feelings of extension, resistance, and all the qualities of matter, is matter; and, to suppose that there is nothing, without us, which excites these feelings, is to suppose, that there is no matter without, as far as we are capable of forming any conception of matter. The system of occasional causes seems, therefore, to be only a more awkward and complicated modification of the system of Berkeley; for, as the Deity is, in this system, himself the author of every change, the only conceivable use of matter, which cannot affect us, more than if it were not in existence, must be as a remembrance, to Him who is Omniscience itself, at what particular moment he is to excite a feeling in the mind of some one of his sensitive creatures, and of what particular kind that feeling is to be; as if the Omniscient could stand in need of any memorial, to excite in our mind any feeling, which it is His wish to excite, and which is to be traced wholly to his own immediate agency. Matter then, according to this system, has no relations to us; and all its relations are to the Deity alone. The assertors of the doctrine, indeed, seem to consider it, as representing, in a more sublime light, the divine Omnipresence, by exhibiting it to our conception, as the only power in nature; but they might, in like manner, affirm, that the creation of the infinity of worlds, with all the life and happiness that are diffused over them, rendered less instead of more sublime, the existence of Him, who, till then, was the sole existence; for power, that is derived, derogates as little from the primary power, as derived existence derogates from the Being from whom it flows. Yet the assertors of this doctrine, who conceive, that light has no effect in vision, are perfectly willing to admit that light exists, or rather, are strenuous affirmers of its existence, and are anxious only to prove, in their zeal, for the glory of Him, who made it, and who makes nothing in vain, that this, and all His works, exist for no purpose. Light, they contend, has no influence whatever. It is as little capable of exciting sensations of colour, as of exciting a sensation of melody or fragrance; but still it exists. The production of so very simple a state as that of vision, or any other of the modes of perception, with an apparatus, which is not merely complicated, but, in all its complication, absolutely without efficacy of any sort, is so far from adding any sublimity to the divine nature, in our conception, that it can scarcely be conceived by the mind, without lessening, in some degree, the sublimity of the Author of the universe, by lessening, or rather destroying, all the sublimity of the universe which he has made. What is that idle mass of matter, which cannot affect us, or be known to us, or to any other created being, more than if it were not? If the Deity produces, in every case, by his own immediate operation, all those feelings which we term sensations or perceptions, he does not first create a multitude of inert and cumbrous worlds, invisible to every eye but his own, and incapable of affecting any thing whatever, that he may know when to operate, as he would have operated before. This is not the awful simplicity of that Omnipresence,