Secondly, Every one who is acquainted with the rules of perspective knows that the appearance of the figure of the book must vary in every different position; yet if you ask a man that has no notion of perspective, whether the figure of it does not appear to his eye to be the same in all its different positions? he can with a good conscience SECT. III.] OF SEEING. 03 affirm, that it does. He hath learned to make allow- ance for the variety of visible figure arising from the dif- ference of position, and to draw the proper conclusions from it. But he draws these conclusions so readily and habitually as to lose sight of the premises; and, therefore, where he hath made the same conclusion, he conceives the visible appearance must have been the same.
Thirdly, Let us consider the apparent magnitude or di- mensions of the book. Whether I view it at the distance of one foot or of ten feet, it seems to be about seven inches long, five broad, and one thick. I can judge of these di- mensions very nearly by the eye, and I judge them to be the same at both distances. But yet it is certain that at the distance of one foot, its visible length and breadth is about ten times as great as at the distance of ten feet; and consequently its surface is about a hundred times as great. This great change of apparent magnitude is altogether overlooked, and every man is apt to imagine, that it ap- pears to the eye of the same size at both distances. Fur- ther, when I look at the book, it seems plainly to have three dimensions, of length, breadth, and thickness: but it is certain that the visible appearance hath no more than two, and can be exactly represented upon a canvass which hath only length and breadth.
In the last place, Does not every man, by sight, per- ceive the distance of the book from his eye? Can he not affirm with certainty, that in one case it is not above one foot distant, that in another it is ten? Nevertheless it ap- pears certain, that distance from the eye is no immediate object of sight. There are certain things in the visible appearance, which are signs of distance from the eye, and from which, as we shall afterwards show, we learn by experience to judge of that distance within certain limits; but it seems beyond doubt, that a man born blind, and suddenly made to see, could form no judgment at first of the distance of the objects which he saw. The young man couched by Cheselden thought, at first, that every thing he saw touched his eye, and learned only by expe- rience to judge of the distance of visible objects.
I have entered into this long detail, in order to show, 94 OF THE HUMAN MIND. [CHAP. VI.
that the visible appearance of an object is extremely dif- ferent from the notion of it which experience teaches us to form by sight; and to enable the reader to attend to the visible appearance of colour, figure, and extension, in visible things, which is no common object of thought, but must be carefully attended to by those who would enter into the philosophy of this sense, or would comprehend what shall be said upon it. To a man newly made to see, the visible appearance of objects would be the same as to us; but he would see nothing at all of their real dimen- sions, as we do. He could form no conjecture, by means of his sight only, how many inches or feet they were in length, breadth, or thickness. He could perceive little or nothing of their real figure; nor could he discern that this was a cube, that a sphere: that this was a cone, and that a cylinder. His eye could not inform him, that this ob- ject was near, and that more remote. The habit of a man or of a woman, which appeared to us of one uniform colour variously folded and shaded, would present to his eye neither fold nor shade, but variety of colour. In a word, his eyes, though ever so perfect, would at first give him almost no information of things without him. They would indeed present the same appearances to him as they do to us, and speak the same language; but to him it is an unknown language, and therefore he would attend only to the signs, without knowing the signification of them: whereas to us it is a language perfectly familiar; and therefore we take no notice of the signs, but attend only to . the thing signified by them.
SECT. IV.
That Colour is a Quality of Bodies, not a Sensation of the Mind.
BY colour, all men, who have not been tutored by modern philosophy, understand, not a sensation of the mind, which can have no existence when it is not perceived, but a qua- lity or modification of bodies, which continues to be the SECT. IV.] OF SEEING. G5 same, whether it is seen or not. The scarlet rose, which is before me, is still a scarlet rose when I shut my eyes, and was so at midnight when no eye saw it. The colour remains when the appearance ceases: it remains the same when the appearance changes. For when I view this scarlet rose through a pair of green spectacles, the ap- pearance is changed, but I do not conceive the colour of the rose changed. To a person in the jaundice, it has still another appearance; but he is easily convinced, that the change is in his eye, and not in the colour of the ob- ject. Eveiy different degree of light makes it have a dif- ferent appearance, and total darkness takes away all ap- pearance, but makes not the least change in the colour of the body. We may, by a variety of optical experiments, change the appearance of figure and magnitude in a body, as well as that of colour; we may make one body appear to be ten. But all men believe, that as a multiplying glass does not really produce ten guineas out of one, nor a microscope turn a guinea into a ten pound piece; so nei- ther does a coloured glass change the real colour of the object seen through it, when it changes the appearance of that colour.
The common language of mankind shows evidently, that we ought to distinguish between the colour of a body, which is conceived to be a fixed and permanent quality in the body, and the appearance of that colour to the eye, which may be varied a thousand ways, by a variation of the light, of the medium, or of the eye itself. The perma- nent colour of the body is the cause, which, by the media- tion of various kinds or degrees of light, and of various transparent bodies interposed, produces all this variety of appearances. When a coloured body is presented, there is a certain apparition to the eye, or to the mind, which we have called the appearance of colour. Mr. Locke calls it an idea; and indeed it may be called so with the greatest propriety. This idea can have no existence but when it is perceived. It is a kind of thought, and can only be the act of a percipient or thinking being. By the constitution of our nature, we are led to conceive this idea 96 OF THE HUMAN MIND. [CHAP. VI, as a sign of something external, and are impatient till we learn its meaning. A thousand experiments for this pur- pose are made every day by children, even before they come to the use of reason. They look at things, they handle them, they put them in various positions, at dif- ferent distances, and in different lights. — The ideas of sight, by these means, come to be associated with, and readily to suggest, things external, and altogether unlike them. In particular, that idea which we have called the appearance of colour suggests the conception and belief of some unknown quality in the body, which occasions the idea; and it is to this quality, and not to the idea, that we give the name of colour. The various colours, although in their nature equally unknown, are easily distinguished when we think or speak of them, by being associated with the ideas which they excite. In like manner, gravity, magnetism, and electricity, although all unknown qualities, are distinguished by their different effects. As we grow up, the mind acquires a habit of passing so rapidly from the ideas of sight to the external things suggested by them that the ideas are not in the least attended to, nor have they names given them in common language.
When we think or speak of any particular colour, how- ever simple the notion may seem to be which is presented to the imagination, it is really in some sort compounded. It involves an unknown cause and a known effect. The name of colour belongs indeed to the cause only, and not to the effect. But as the cause is unknown, we can form no distinct conception of it, but by its relation to the known effect. And therefore, both go together in the imagination, and are so closely united that they are mis- taken for one simple object of thought. When I would conceive those colours of bodies which we call scarlet and blue; if I. conceived them only as unknown qualities, I could perceive no distinction between the one and the other. I must therefore, for the sake of distinction, join to each of them, in my imagination, some effect or some relation that is peculiar. And the most obvious distinction is, the appearance which one and the other makes to the SECT. IV.] OF SEEING. 9?
eye. Hence the appearance is, in the imagination, so closely united with the quality called a scarlet colour that they are apt to be mistaken for one and the same thing, although they are in reality so different and so un- like that one is an idea in the mind, the other is a quality of body.
I conclude, then, that colour is not a sensation, but a secondary quality of bodies, in the sense we have already explained; that it is a certain power or virtue in bodies, that in fair daylight exhibits to the eye an appearance which is very familiar to us, although it hath no name. Colour differs from other secondary qualities in this, that .whereas the name of the quality is sometimes given to the sensation which indicates it, and is occasioned by it, we never, as far as I can judge, give the name of colour to the sensation but to the quality only. Perhaps the reason of this may be, that the appearances of the same colour are so various and changeable, according to the different modifications of the light, of the medium, and of the eye, that language could not afford names for them. And in- deed they are so little interesting that they are never at- tended to, but serve only as signs to introduce the things signified by them. Nor ought it to appear incredible, that appearances so frequent and so familiar should have no names, nor be made objects of thought: since we have before shown, that this is true of many sensations of touch, which are no less frequent, nor less familiar.
SECT. V.
An Inference from the preceding.
FROM what hath been said about colour, we may infer two things. The first is, that one of the most remarkable paradoxes of modern philosophy, which hath been univer- sally esteemed as a great discovery, is, in reality, when examined to the bottom, nothing else but an abuse of words. The paradox I mean is, That colour is not a F 98 OF THE HUMAN MIND. [CHAP. VI.
quality of bodies, but only an idea in the mind. We have shown that the word colour, as used by the vulgar, cannot signify an idea in the mind, but a permanent quality of body. We have shown that there is really a permanent quality of body, to which the common use of this word exactly agrees. Can any stronger proof be desired, that this quality is that to which the vulgar give the name of colour? If it should be said, that this quality, to which we give the name of colour, is unknown to the vulgar, and therefore can have no name among them; I answer, it is indeed known only by its effects; that is, by its exciting a certain idea in us: but are there not numberless qualities of bodies, which are known only by their effects, to which, notwithstanding, we find it necessary to give names? Medicine alone might furnish us with a hundred instances of this kind. Do not the words astringent, narcotic, cpispastic, caustic, and innumerable others, signify qualities of bodies, which are known only by their effects upon animal bodies? Why then should not the vulgar give a name to a quality, whose effects are every moment perceived by their eyes? We have all the reason, therefore, that the nature of the thing admits, to think that the vulgar apply the name of colour to that quality of bodies, which excites in us what the philosophers call the idea of colour. And that there is such a quality in bodies, all philosophers allow, who allow that there is any such thing as body. Philosophers have thought fit to leave that quality of bodies, which the vulgar call colour, without a name, and to give the name of colour to the idea or appearance, to which, as we have shown, the vulgar give no name, because they never make it an object of thought or reflection. Hence it appears, that when philosophers affirm that colour is not in bodies, but in the mind; and the vulgar affirm, that colour is not in the mind, but is a quality of bodies, there is no dif- ference between them about things, but only about the meaning of a word.
The vulgar have undoubted right to give names to things which they are daily conversant about; and phi- losophers seem justly chargeable with an abuse of Ian- SECT. V.] OF SEEING. 99 guage, when they change the meaning of a common word, without giving warning.
If it is a good rule, to think with philosophers and speak with the vulgar, it must be right to speak with the vulgar when we think with them, and not to shock them by phi- losophical paradoxes, which, when put into common lan- guage, express only the common sense of mankind.
If you ask a man that is no philosopher, what colour is? or, what makes one body appear white, another scarlet? He cannot tell. He leaves that inquiry to philosophers, and can embrace any hypothesis about it, except that of our modern philosophers, who affirm that colour is not in body, but only in the mind.
Nothing appears more shocking to his apprehension than that visible objects should have no colour, and that colour should be in that which he conceives to be invi- sible. Yet this strange paradox is not only universally received, but considered as one of the noblest discoveries of modern philosophy. The ingenious Addison, in the Spectator, No. 413, speaks thus of it: "I have here sup- posed, that my reader is acquainted with that great mo- dern discoveiy, which is at present universally acknow- ledged by all the inquirers into natural philosophy, namely, that light and colours, as apprehended by the imagination, are only ideas in the mind, and not qualities that have any existence in matter. As this is a truth, which has been proved incontestably by many modern philosophers, and is indeed one of the finest speculations in that science, if the English reader would see the notion explained at large, he may find it in the eighth chapter of the second book of Locke's Essay on Human Understanding " Mr. Locke and Mr. Addison are writers who have de- served so well of mankind that one must feel some un- easiness in differing from them, and would wish to ascribe all the merit that is due to a discovery upon which they put so high a value. And indeed it is just to acknow- ledge, that Locke, and other modern philosophers on the subject of secondary qualities, have the merit of distin- guishing more accurately than those that went before F2 100 OF THE HUMAN MIND. [CHAP. VI.
them, between the sensation in the mind and that consti- tution or quality of bodies which gives occasion to the sensation. They have shown clearly that these two things are not only distinct, but altogether unlike: that there is no similitude between the effluvia of an odorous body and the sensation of smell, or between the vibrations of a sounding body and the sensation of sound: that there can be no resemblance between the feeling of heat and the constitution of the heated body which occasions it; or be- tween the appearance which a coloured body makes to the eye and the texture of the body which causes that ap- pearance.
Nor was the merit small of distinguishing these things accurately; because, however different and unlike in their nature, they have been always so associated in the imagi- nation as to coalesce as it were into one two-faced form, which, from its amphibious nature, could not justly be appropriated either to body or mind; and, until it was properly distinguished into its different constituent parts, it was impossible to assign to either their just shares in it. None of the ancient philosophers had made this distinc- tion. The followers of Democritus and Epicurus con- ceived the forms of the heat, and sound, and colour, to be in the mind only, but that our senses fallaciously repre- sented them as being in bodies. The Peripatetics ima- gined, that those forms are really in bodies? and that the images of them are conveyed to the mind by our senses.
The one system made the senses naturally fallacious and deceitful; the other made the qualities of body to resemble the sensations of the mind. Now was it possible to find a third without making the distinction we have mentioned; by which indeed the errors of both these ancient systems are avoided, and we are not left under the hard necessity of believing, either, on the one hand, that our sensations are like to the qualities of body, or on the other, that God hath given us one faculty to deceive us, and another to detect the cheat.
We desire, therefore, with pleasure, to do justice to the doctrine of Locke and other modern philosophers, with SECT. V.] OF SEEING. 101 regard to colour and other secondary qualities, and to ascribe to it its due merit, while we beg leave to censure the language in which they have expressed their doctrine. When they had explained and established the distinction between the appearance which colour makes to the eye, and the modification of the coloured body, which, by the laws of Nature, causes that appearance; the question was, whether to give the name of colour to the cause, or to the effect? By giving it, as they have done, to the effect, they set philosophy apparently in opposition to common sense, and expose it to the ridicule of the vulgar. But, had they given the name of colour to the cause as they ought to have done, they must then have affirmed, with the vulgar, that colour is a quality of bodies; and that there is neither colour, nor any thing like it, in the mind. Their language, as well as their sentiments, would have been perfectly agreeable to the common apprehen- sions of mankind, and true philosophy would have joined hands with Common Sense. As Locke was no enemy to common sense, it may be presumed, that, in this instance, as in some others, he was seduced by some received hy- pothesis: and, that this was actually the case, will appear in the following: section.
SECT. VI.
That none of our Sensations are Resemblances of any of the Qualities of Bodies.
A SECOND inference is, That although colour is really a quality of body, yet it is not represented to the mind by an idea or sensation that resembles it; on the contrary, it is suggested by an idea which does not in the least resemble it. — And this inference is applicable, not to colour only, but to all the qualities of body which we have examined.
It deserves to be remarked, that in the analysis we have hitherto given of the operations of the five senses, and of the qualities of bodies discovered by them, no instance hath occurred, either of any sensation which resembles any 102 OF THE HUMAN MIND. [CHAP. VI.
quality of body, or of any quality of body whose image or resemblance is conveyed to the mind by means of the senses.
There is no phenomenon in nature more unaccountable than the intercourse that is carried on between the mind and the external world; there is no phenomenon which philosophical spirits have shown greater avidity to pry into and to resolve. It is agreed by all, that this intercourse is carried on by means of the senses; and this satisfies the vulgar curiosity, but not the philosophic. Philoso- phers must have some system, some hypothesis, that shows the manner in which our senses make us acquainted with external things. All the fertility of human invention seems to have produced only one hypothesis for this purpose, which therefore hath been universally received; and that is, that the mind, like the mirror, receives the images of things from without, by means of the senses; so that their use must be to convey these images into the mind.
Whether to these images of external things in the mind, we give the name of sensible forms or sensible pieces, with the Peripatetics, or the name of ideas of sensation, with Locke; or whether, with later philosophers, we distinguish sensations, which are immediately conveyed by the senses, from ideas of sensation, which are faint copies of our sen- sations retained in the memory and imagination; these are only differences about words. The hypothesis I have mentioned is common to all these different systems.
The necessary and allowed consequence of this hypo- thesis is, That no material thing, nor any quality of mate- rial things, can be conceived by us, or made an object of thought, until its image is conveyed to the mind by means of the senses. We shall examine this hypothesis particu- larly afterwards, and at this time only observe, that, in consequence of it, one would naturally expect, that to every quality or attribute of body we know or can conceive, there should be a sensation corresponding, which is the image and resemblance of that quality; and that the sensations which have no similitude or resemblance to body or to any of its qualities should give us no conception of a ma- terial world, or of any thing belonging to it. These things SECT. VI.] OF SEEING. 103 might be expected as the natural consequence of the hy- pothesis we have mentioned.
Now, we have considered, in this and the preceding chapters, extension, figure, solidity, motion, hardness, roughness, as well as colour, heat and cold, sound, taste, and smell. We have endeavoured to show, that our na- ture and constitution lead us to conceive these as qualities of body, as all mankind have always conceived them to be. We have likewise examined, with great attention, the various sensations we have by means of the five senses, and are not able to find among them all one single image of body or of any of its qualities. From whence then come those images of body and of its qualities into the mind? Let philosophers resolve this question. All I can say is, that they come not by the senses. I am sure, that, by proper attention and care, I may know my sensations, and be able to affirm with certainty what they resemble, and what they do not resemble. I have examined them one by one, and compared them with matter and its qua- lities; and I cannot find one of them that confesses a re- sembling feature.
A truth so evident as this, That our sensations are not images of matter, or of any of its qualities, ought not to yield to an hypothesis such as that abovementioned, how- ever ancient, or however universally received by philoso- phers; nor can there be any amicable union between the two. This will appear by some reflections upon the spirit of the ancient and modern philosophy concerning sen- sation.
During the reign of the Peripatetic philosophy, our sen- sations were not mutually or accurately examined. The attention of philosophers, as well as of the vulgar, was turned to the things signified by them: therefore, in conse- quence of the common hypothesis, it was taken for granted, that all the sensations we have from external things are the forms or images of these external things. And thus the truth we have mentioned yielded entirely to the hypothesis, and was altogether suppressed by it.
Des Cartes gave a noble example of turning our atten- 104 OF THE HUMAN MIND. [CHAP. VI.
tion inward, and scrutinizing our sensations; and this example hath been very worthily followed by modern phi- losophers, particularly by Malebranche, Locke, Berkeley, and Hume. The effect of this scrutiny hath been a gra- dual discoveiy of the truth abovementioned, to wit, the dissimilitude between the sensations of our minds and the qualities or attributes of an insentient inert substance, such as we conceive matter to be. But this valuable and useful discovery, in its different stages, hath still been unhappily united to the ancient hypothesis; and, from this inauspicious match of opinions, so unfriendly and discor- dant in their natures, have arisen those monsters of para- dox and scepticism with which the modern philosophy is too justly chargeable.
Locke saw clearly, and proved incontestably, that the sensations we have by taste, smell, and hearing, as well as the sensations of colour, heat, and cold, are not resem- blances of any thing in bodies; and in this he agrees with Des Cartes and Malebranche. Joining this opinion with the hypothesis, it follows necessarily, that three senses of the five are cut off from giving us any intelligence of the material world, as being altogether inept for that office. Smell and taste and sound, as well as colour and heat, can have no more relation to body than anger or gratitude; nor ought the former to be called qualities of body, whe- ther primary or secondary, any more than the latter. For it was natural and obvious to argue thus from that hypo- thesis: if heat and colour and sound are real qualities of body, the sensations, by which we perceive them, must be resemblances of those qualities; but these sensations are not resemblances; therefore those are not real quali- ties of body.
We see then, that Locke, having found that the ideas of secondaiy qualities are no resemblances, was compelled, by an hypothesis common to all philosophers, to deny that they are real qualities of body. It is more difficult to assign a reason, why, after this he should call them secon- dary qualities; for this name, if I mistake not, was of his invention. Surely he did not mean that they were secon- SECT. VI.] OF SEEING. lOo dary qualities of the mind; and I do not see with what propriety, or even by what tolerable licence, he could call them secondary qualities of body, after finding that they were no qualities of body at all. In this he seems to have sacrificed to Common Sense, and to have been led by her authority, even in opposition to his hypothesis. The same sovereign mistress of our opinions that led this philosopher to call those things secondary qualities of body, which, according to his principles and reasonings, were no qua- lities of body at all, hath led, not the vulgar of all ages only, but philosophers also, and even the disciples of Locke, to believe them to be real qualities of body: she hath led them to investigate, by experiments, the nature of colour, and sound, and heat in bodies. Nor hath this investigation been fruitless, as it must have been if there had been no such thing in bodies: on the contrary, it hath produced very noble and useful discoveries, which make a very considerable part of natural philosophy. If then natural philosophy be not a dream, there is something in bodies, which we call colour, and heat, and sound. And if this be so, the hypothesis from which the contrary is concluded must be false: for the argument, leading to a false conclusion, recoils against the hypothesis from which it was drawn, and thus directs its force backward. If the qualities of body were known to us only by sensations that, resemble them, then colour, and sound, and heat, could be no qualities of body; but these are real qualities of body, and therefore the qualities of body are not known only by means of sensations that resemble them.