An Essay Concerning Human Understanding/Book II/Chapter IX
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Chapter IX: Of Perception
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1. Perception the first simple idea of reflection. Perception, as it is the first faculty of the mind exercised about our ideas ; so it is the first and simplest idea we have from reflection, and is by some called thinking in general. Though thinking, in the propriety of the English tongue, signifies that sort of operation in the mind about its ideas, wherein the mind is active ; where it, with some degree of voluntary attention, considers anything. For in bare naked perception, the mind is, for the most part, only passive ; and what it perceives, it cannot avoid perceiving.
2. Reflection alone can give us the idea of what perception is. What perception is, every one will know better by reflecting on what he does himself, when he sees, hears, feels, &c., or thinks, than by any discourse of mine. Whoever reflects on what passes in his own mind cannot miss it. And if he does not reflect, all the words in the world cannot make him have any notion of it.
3. Arises in sensation only when the mind notices the organic impression. This is certain, that whatever alterations are made in the body, if they reach not the mind ; whatever impressions are made on the outward parts, if they are not taken notice of within, there is no perception. Fire may burn our bodies with no other effect than it does a billet, unless the motion be continued to the brain, and there the sense of heat, or idea of pain, be produced in the mind ; wherein consists actual perception.
4. Impulse on the organ insufficient. How often may a man observe in himself, that whilst his mind is intently employed in the contemplation of some objects, and curiously surveying some ideas that are there, it takes no notice of impressions of sounding bodies made upon the organ of hearing, with the same alteration that uses to be for the producing the idea of sound ? A sufficient impulse there may be on the organ ; but it not reaching the observation of the mind, there follows no perception : and though the motion that uses to produce the idea of sound be made in the ear, yet no sound is heard. Want of sensation, in this case, is not through any defect in the organ, or that the man’s ears are less affected than at other times when he does hear : but that which uses to produce the idea, though conveyed in by the usual organ, not being taken notice of in the understanding, and so imprinting no idea in the mind, there follows no sensation. So that wherever there is sense or perception, there some idea is actually produced, and present in the understanding.
5. Children, though they may have ideas in the womb, have none innate. Therefore I doubt not but children, by the exercise of their senses about objects that affect them in the womb, receive some few ideas before they are born, as the unavoidable effects, either of the bodies that environ them, or else of those wants or diseases they suffer ; amongst which (if one may conjecture concerning things not very capable of examination) I think the ideas of hunger and warmth are two : which probably are some of the first that children have, and which they scarce ever part with again.
6. The effects of sensation in the womb. But though it be reasonable to imagine that children receive some ideas before they come into the world, yet these simple ideas are far from those innate principles which some contend for, and we, above, have rejected. These here mentioned, being the effects of sensation, are only from some affections of the body, which happen to them there, and so depend on something exterior to the mind ; no otherwise differing in their manner of production from other ideas derived from sense, but only in the precedency of time. Whereas those innate principles are supposed to be quite of another nature ; not coming into the mind by any accidental alterations in, or operations on the body ; but, as it were, original characters impressed upon it, in the very first moment of its being and constitution.
7. Which ideas appear first, is not evident, nor important. As there are some ideas which we may reasonably suppose may be introduced into the minds of children in the womb, subservient to the necessities of their life and being there : so, after they are born, those ideas are the earliest imprinted which happen to be the sensible qualities which first occur to them ; amongst which light is not the least considerable, nor of the weakest efficacy. And how covetous the mind is to be furnished with all such ideas as have no pain accompanying them, may be a little guessed by what is observable in children new-born ; who always turn their eyes to that part from whence the light comes, lay them how you please. But the ideas that are most familiar at first, being various according to the divers circumstances of children’s first entertainment in the world, the order wherein the several ideas come at first into the mind is very various, and uncertain also ; neither is it much material to know it.
8. Sensations often changed by the judgment. We are further to consider concerning perception, that the ideas we receive by sensation are often, in grown people, altered by the judgment, without our taking notice of it. When we set before our eyes a round globe of any uniform colour, v.g. gold, alabaster, or jet, it is certain that the idea thereby imprinted on our mind is of a flat circle, variously shadowed, with several degrees of light and brightness coming to our eyes. But we having, by use, been accustomed to perceive what kind of appearance convex bodies are wont to make in us ; what alterations are made in the reflections of light by the difference of the sensible figures of bodies ; – the judgment presently, by an habitual custom, alters the appearances into their causes. So that from that which is truly variety of shadow or colour, collecting the figure, it makes it pass for a mark of figure, and frames to itself the perception of a convex figure and an uniform colour ; when the idea we receive from thence is only a plane variously coloured, as is evident in painting. To which purpose I shall here insert a problem of that very ingenious and studious promoter of real knowledge, the learned and worthy Mr. Molyneux, which he was pleased to send me in a letter some months since ; and it is this : – « Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere of the same metal, and nighly of the same bigness, so as to tell, when he felt one and the other, which is the cube, which the sphere. Suppose then the cube and sphere placed on a table, and the blind man be made to see : quaere, whether by his sight, before he touched them, he could now distinguish and tell which is the globe, which the cube ? » To which the acute and judicious proposer answers, « Not. For, though he has obtained the experience of how a globe, how a cube affects his touch, yet he has not yet obtained the experience, that what affects his touch so or so, must affect his sight so or so ; or that a protuberant angle in the cube, that pressed his hand unequally, shall appear to his eye as it does in the cube. » – I agree with this thinking gentleman, whom I am proud to call my friend, in his answer to this problem ; and am of opinion that the blind man, at first sight, would not be able with certainty to say which was the globe, which the cube, whilst he only saw them ; though he could unerringly name them by his touch, and certainly distinguish them by the difference of their figures felt. This I have set down, and leave with my reader, as an occasion for him to consider how much he may be beholden to experience, improvement, and acquired notions, where he thinks he had not the least use of, or help from them. And the rather, because this observing gentleman further adds, that « having, upon the occasion of my book, proposed this to divers very ingenious men, he hardly ever met with one that at first gave the answer to it which he thinks true, till by hearing his reasons they were convinced. »
9. This judgment apt to be mistaken for direct perception. But this is not, I think, usual in any of our ideas, but those received by sight. Because sight, the most comprehensive of all our senses, conveying to our minds the ideas of light and colours, which are peculiar only to that sense ; and also the far different ideas of space, figure, and motion, the several varieties whereof change the appearances of its proper object, viz. light and colours ; we bring ourselves by use to judge of the one by the other. This, in many cases by a settled habit, – in things whereof we have frequent experience, is performed so constantly and so quick, that we take that for the perception of our sensation which is an idea formed by our judgment ; so that one, viz. that of sensation, serves only to excite the other, and is scarce taken notice of itself ; – as a man who reads or hears with attention and understanding, takes little notice of the characters or sounds, but of the ideas that are excited in him by them.
10. How, by habit, ideas of sensation are unconsciously changed into ideas of judgment. Nor need we wonder that this is done with so little notice, if we consider how quick the actions of the mind are performed. For, as itself is thought to take up no space, to have no extension ; so its actions seem to require no time, but many of them seem to be crowded into an instant. I speak this in comparison to the actions of the body. Any one may easily observe this in his own thoughts, who will take the pains to reflect on them. How, as it were in an instant, do our minds, with one glance, see all the parts of a demonstration, which may very well be called a long one, if we consider the time it will require to put it into words, and step by step show it another ? Secondly, we shall not be so much surprised that this is done in us with so little notice, if we consider how the facility which we get of doing things, by a custom of doing, makes them often pass in us without our notice. Habits, especially such as are begun very early, come at last to produce actions in us, which often escape our observation. How frequently do we, in a day, cover our eyes with our eyelids, without perceiving that we are at all in the dark ! Men that, by custom, have got the use of a by-word, do almost in every sentence pronounce sounds which, though taken notice of by others, they themselves neither hear nor observe. And therefore it is not so strange, that our mind should often change the idea of its sensation into that of its judgment, and make one serve only to excite the other, without our taking notice of it.
11. Perception puts the difference between animals and vegetables. This faculty of perception seems to me to be, that which puts the distinction betwixt the animal kingdom and the inferior parts of nature. For, however vegetables have, many of them, some degrees of motion, and upon the different application of other bodies to them, do very briskly alter their figures and motions, and so have obtained the name of sensitive plants, from a motion which has some resemblance to that which in animals follows upon sensation : yet I suppose it is all bare mechanism ; and no otherwise produced than the turning of a wild oat-beard, by the insinuation of the particles of moisture, or the shortening of a rope, by the affusion of water. All which is done without any sensation in the subject, or the having or receiving any ideas.
12. Perception in all animals. Perception, I believe, is, in some degree, in all sorts of animals ; though in some possibly the avenues provided by nature for the reception of sensations are so few, and the perception they are received with so obscure and dull, that it comes extremely short of the quickness and variety of sensation which is in other animals ; but yet it is sufficient for, and wisely adapted to, the state and condition of that sort of animals who are thus made. So that the wisdom and goodness of the Maker plainly appear in all the parts of this stupendous fabric, and all the several degrees and ranks of creatures in it.
13. According to their condition. We may, I think, from the make of an oyster or cockle, reasonably conclude that it has not so many, nor so quick senses as a man, or several other animals ; nor if it had, would it, in that state and incapacity of transferring itself from one place to another, be bettered by them. What good would sight and hearing do to a creature that cannot move itself to or from the objects wherein at a distance it perceives good or evil ? And would not quickness of sensation be an inconvenience to an animal that must lie still where chance has once placed it, and there receive the afflux of colder or warmer, clean or foul water, as it happens to come to it ?
14. Decay of perception in old age. But yet I cannot but think there is some small dull perception, whereby they are distinguished from perfect insensibility. And that this may be so, we have plain instances, even in mankind itself. Take one in whom decrepit old age has blotted out the memory of his past knowledge, and clearly wiped out the ideas his mind was formerly stored with, and has, by destroying his sight, hearing, and smell quite, and his taste to a great degree, stopped up almost all the passages for new ones to enter ; or if there be some of the inlets yet half open, the impressions made are scarcely perceived, or not at all retained. How far such an one (notwithstanding all that is boasted of innate principles) is in his knowledge and intellectual faculties above the condition of a cockle or an oyster, I leave to be considered. And if a man had passed sixty years in such a state, as it is possible he might, as well as three days, I wonder what difference there would be, in any intellectual perfections, between him and the lowest degree of animals.
15. Perception the inlet of all materials of knowledge. Perception then being the first step and degree towards knowledge, and the inlet of all the materials of it ; the fewer senses any man, as well as any other creature, hath ; and the fewer and duller the impressions are that are made by them, and the duller the faculties are that are employed about them, – the more remote are they from that knowledge which is to be found in some men. But this being in great variety of degrees (as may be perceived amongst men) cannot certainly be discovered in the several species of animals, much less in their particular individuals. It suffices me only to have remarked here, – that perception is the first operation of all our intellectual faculties, and the inlet of all knowledge in our minds. And I am apt too to imagine, that it is perception, in the lowest degree of it, which puts the boundaries between animals and the inferior ranks of creatures. But this I mention only as my conjecture by the by ; it being indifferent to the matter in hand which way the learned shall determine of it.