‘The first of these, as has been said, I think, may be properly called, real, original, or primary qualities, because they are in the things themselves, whether they are perceived or no: and upon their different modifications it is that the secondary qualities depend. The other two are only powers to act differently upon other things, which powers result from the different modifications of those primary qualities.
‘But though these two latter sorts of qualities are powers barely, and nothing but powers, relating to several other bodies, and resulting from the different modifications of the original qualities, yet they are generally thought otherwise of. For the second sort, viz., the powers to produce several ideas in us by our senses, are looked upon as real qualities in the things thus affecting us: but the third sort are called and esteemed barely powers. For example, the ideas of heat or light, which we receive by our eye or touch from the sun are commonly thought real qualities, existing in the sun, and something more than mere powers in it. But when we consider the sun in reference to wax which it melts or blanches, we look on the whiteness and softness produced in the wax, not as qualities in the sun, but effects produced by powers in it: whereas, if rightly considered, these qualities of light and warmth, which are perceptions in me when I am warmed or enlightened by the sun, are no otherwise in the sun than the changes made in the wax, when it is blanched or melted, are in the sun. They are all of them equally powers in the sun, depending on its primary qualities: whereby it is enabled in the one case so to alter the bulk, figure, texture, or motion of some of the insensible parts of my eyes or hands, as thereby to produce in me the idea of light or heat; and in the other, it is able so to alter the bulk, figure, texture, or motion of the insensible parts of the wax, as to make them fit to produce in me the distinct ideas of white and fluid. The reason why the one are ordinarily taken for real qualities, and the other only for bare powers, seems to be, because the ideas we have of distinct colours, sounds, &c., containing nothing at all in them of bulk, figure, or motion, we are not apt to think them the effects of those primary qualities which appear not to our senses to operate in their production, and with which they have not any apparent congruity or conceivable connexion. Hence it is that we are so forward to imagine that those ideas are the resemblances of something really existing in the objects themselves. But in the other case, in the operation of bodies, changing the qualities, one of another, we plainly discover that the quality produced hath commonly no resemblance with any thing in the thing producing it; wherefore we look on it as a bare effect of power. For though receiving the idea of heat or light from the sun, we are apt to think it is a perception and resemblance of such a quality in the sun, yet when we see wax or a fair face receive change of colour from the sun, we cannot imagine that to be the perception or resemblance of any thing in the sun, because we find not those different colours in the sun itself. For our senses being able to observe a likeness or unlikeness of sensible qualities in two different external objects, we forwardly enough conclude the production of any sensible quality in any subject to be an effect of bare power, and not the communication of any quality, which was really in the efficient, when we find no such sensible quality in the thing that produced it. But ourselves not being able to discover any unlikeness between the idea produced in us and the quality of the object producing it, we are apt to imagine that our ideas are resemblances of some thing in the objects, and not the effects of certain powers placed in the modification of their primary qualities, with which primary qualities the ideas produced in us have no resemblance.’ Vol. i. page 127.
From the secondary qualities later writers, as Hume and Berkeley, have proceeded to the primary ones, and have endeavoured to shew that they have not a real existence out of the mind, any more than the others. Hume says, ‘The fundamental principle of the modern philosophy is the opinion concerning colours, sounds, tastes, smells, heat and cold,’ &c.; and Bishop Berkeley has made use of the same principle to banish the least particle of matter out of the universe. What Hume has said is merely taken from Berkeley, from whom his opinions are generally borrowed. As I do not know that I shall have a better opportunity, I will here state Berkeley’s arguments against the existence of these primary qualities, or his ideal system, in his own words. I will only first observe, on the argument against the existence of the secondary qualities of things, from their different effects in different circumstances and on different persons, which Hume considers as the only solid one, but which Berkeley thinks more doubtful, seems to me no argument at all; for that an object changes its colour, or food its taste, is in consequence of distance or of the interposition of another object, or of the indisposition of the organ, and does not prove that the object has not a particular colour, or the food a particular taste, but that colour is combined with and altered by the colour of the air, and that taste is combined with and altered by another taste in the mouth or stomach. The logical inference is merely that one object has not the same sensible qualities as another, or, as Berkeley has remarked, that we do not know what the true or natural qualities of any object are.
‘It is evident,’ says Bishop Berkeley, ‘to any one who takes a survey of the objects of Human Knowledge, that they are either ideas actually imprinted on the senses, or else such as are perceived by attending to the passions and operations of the mind, or, lastly, ideas formed by help of memory and imagination; either compounding, dividing, or barely representing those originally perceived in the aforesaid ways. By sight I have the ideas of light and colours, with their several degrees and variations. By touch I perceive hard and soft, heat and cold, motion and resistance, &c. and of all these more and less, either as to quantity or degree. Smelling furnishes me with odours: the palate with tastes; and hearing conveys sounds to the mind in all their variety of tone and composition. And as several of these are observed to accompany each other, they come to be marked by one name, and so to be reputed as one thing. Thus, for example, a certain colour, taste, smell, figure, and consistence, having been observed to go together, are accounted one distinct thing, signified by the name apple. Other collections of ideas constitute a stone, a tree, a book, and the like sensible things; which, as they are pleasing or disagreeable, excite the passions of love, hatred, joy, grief, &c.
‘2. But besides all that endless variety of ideas or objects of knowledge, there is likewise something which knows and perceives them, and exercises divers operations, as willing, imagining, remembering, &c. about them. This perceiving, active being is what I call mind, spirit, soul, or myself. By which words I do not denote any one of my ideas, but a thing entirely distinct from them, wherein they exist, or, which is the same thing, whereby they are perceived, for the existence of an idea consists in being perceived.
‘3. That neither our thoughts, nor passions, nor ideas formed by the imagination, exist without the mind, is what every body will allow; and to me it is no less evident that the various sensations or ideas imprinted on the sense, however blended or combined together, (that is, whatever objects they compose,) cannot exist otherwise than in a mind perceiving them. I think an intuitive knowledge may be obtained of this, by any one that shall attend to what is meant by the term exist, when applied to sensible things. The table I write on, I say, exists; i.e. I see and feel it, and if I were out of my study, I should say it existed, meaning thereby, that if I was in my study I might perceive it, or that some other spirit actually does perceive it. There was an odour, i.e. it was smelt; there was a sound, i.e. it was heard; a colour or figure, and it was perceived by sight or touch. This is all that I can understand by these and the like expressions. For as to what is said of the absolute existence of unthinking things without any relation to their being perceived, that is to me perfectly unintelligible. Their esse is percipi, nor is it possible they should have any existence, out of the minds or thinking things which perceive them.
‘4. It is indeed an opinion strangely prevailing among men, that houses, mountains, rivers, and in a word all sensible objects, have an existence natural or real, distinct from their being perceived by the understanding. But with how great an assurance and acquiescence soever this principle may be entertained in the world, yet whoever shall find in his heart to call it in question, may, if I mistake not, perceive it to involve a manifest contradiction. For what are the forementioned objects but the things we perceive by sense, and what, I pray you, do we perceive besides our own ideas or sensations? And is it not plainly repugnant that any one of these, or any combination of them, should exist unperceived?
‘5. If we thoroughly examine this tenet, it will, perhaps, be found at bottom to depend on the doctrine of abstract ideas. For can there be a nicer strain of abstraction than to distinguish the existence of sensible objects from their being perceived, so as to conceive them existing unperceived? Light and colours, heat and cold, extension and figures, in a word, the things we see and feel, what are they but so many sensations, notions, ideas, or impressions on the sense; and is it possible to separate, even in thought, any of these from perception? For my part, I might as easily divide a thing from itself. I may, indeed, divide in my thoughts, or conceive apart from each other, those things which, perhaps, I never perceived by sense so divided. Thus I imagine the trunk of a human body without the limbs, or conceive the smell of a rose without thinking on the rose itself. So far I will not deny I can abstract, if that may be properly called abstraction which extends only to the conceiving separately such objects as it is possible may really exist or be actually perceived asunder. But my conceiving or imagining power does not extend beyond the possibility of real existence or perception. Hence, as it is impossible for me to see or feel any thing without an actual sensation of that thing, so it is impossible for me to conceive in my thoughts any sensible thing or object distinct from the sensation or perception of it. In truth, the object and the sensation are the same thing, and cannot therefore be extracted from each other.
‘6. Some truths there are so near and obvious to the mind that a man need only open his eyes to see them. Such I take this important one to be, viz. that all the choir of heaven, and furniture of the earth, in a word, all those bodies which compose the mighty frame of the world, have not any subsistence without a mind, that their esse is to be perceived or known; that consequently, so long as they are not actually perceived by me, or do not exist in my mind or that of any other created spirit, they must either have no existence at all, or else subsist in the mind of some eternal spirit: it being perfectly unintelligible, and involving all the absurdity of abstraction, to attribute to any single part of them an existence independent of a spirit. To make this appear with all the light and evidence of an axiom, it seems sufficient if I can but awaken the reflection of the reader, that he may take an impartial view of his own meaning, and turn his thoughts upon the subject itself, free and disengaged from all embarrass of words and prepossession in favour of received mistakes.
‘7. From what has been said, it is evident there is not any other substance than spirit, or that which perceives. But for the fuller demonstration of this point, let it be considered, the sensible qualities are colour, figure, motion, smell, taste, &c.; i.e. the ideas perceived by sense. Now, for an idea to exist in an unperceiving thing is a manifest contradiction; for to have an idea is all one as to perceive; that, therefore, wherein colour, figure, &c. exist must perceive them. Hence it is clear there can be no unthinking substance or substratum of those ideas.