Part 9

PHIL. The point will be past all doubt, if you consider that, in case colours were real properties or affections inherent in external bodies, they could admit of no alteration without some change wrought in the very bodies themselves: but, is it not evident from what hath been said that, upon the use of microscopes, upon a change happening in the burnouts of the eye, or a variation of distance, without any manner of real alteration in the thing itself, the colours of any object are either changed, or totally disappear? Nay, all other circumstances remaining the same, change but the situation of some objects, and they shall present different colours to the eye. The same thing happens upon viewing an object in various degrees of light. And what is more known than that the same bodies appear differently coloured by candle-light from what they do in the open day? Add to these the experiment of a prism which, separating the heterogeneous rays of light, alters the colour of any object, and will cause the whitest to appear of a deep blue or red to the naked eye. And now tell me whether you are still of opinion that every body hath its true real colour inhering in it; and, if you think it hath, I would fain know farther from you, what certain distance and position of the object, what peculiar texture and formation of the eye, what degree or kind of light is necessary for ascertaining that true colour, and distinguishing it from apparent ones.

HYL. I own myself entirely satisfied, that they are all equally apparent, and that there is no such thing as colour really inhering in external bodies, but that it is altogether in the light. And what confirms me in this opinion is, that in proportion to the light colours are still more or less vivid; and if there be no light, then are there no colours perceived. Besides, allowing there are colours on external objects, yet, how is it possible for us to perceive them? For no external body affects the mind, unless it acts first on our organs of sense. But the only action of bodies is motion; and motion cannot be communicated otherwise than by impulse. A distant object therefore cannot act on the eye; nor consequently make itself or its properties perceivable to the soul. Whence it plainly follows that it is immediately some contiguous substance, which, operating on the eye, occasions a perception of colours: and such is light.

PHIL. Howl is light then a substance?

HYL. . I tell you, Philonous, external light is nothing but a thin fluid substance, whose minute particles being agitated with a brisk motion, and in various manners reflected from the different surfaces of outward objects to the eyes, communicate different motions to the optic nerves; which, being propagated to the brain, cause therein various impressions; and these are attended with the sensations of red, blue, yellow, &c.

PHIL. It seems then the light doth no more than shake the optic nerves.

HYL. Nothing else.

PHIL. And consequent to each particular motion of the nerves, the mind is affected with a sensation, which is some particular colour.

HYL. Right.

PHIL. And these sensations have no existence without the mind.

HYL. They have not.

PHIL. How then do you affirm that colours are in the light; since by LIGHT you understand a corporeal substance external to the mind?

HYL. Light and colours, as immediately perceived by us, I grant cannot exist without the mind. But in themselves they are only the motions and configurations of certain insensible particles of matter.

PHIL. Colours then, in the vulgar sense, or taken for the immediate objects of sight, cannot agree to any but a perceiving substance.

HYL. That is what I say.

PHIL. Well then, since you give up the point as to those sensible qualities which are alone thought colours by all mankind beside, you may hold what you please with regard to those invisible ones of the philosophers. It is not my business to dispute about THEM; only I would advise you to bethink yourself, whether, considering the inquiry we are upon, it be prudent for you to affirm--THE RED AND BLUE WHICH WE SEE ARE NOT REAL COLOURS, BUT CERTAIN UNKNOWN MOTIONS AND FIGURES WHICH NO MAN EVER DID OR CAN SEE ARE TRULY SO. Are not these shocking notions, and are not they subject to as many ridiculous inferences, as those you were obliged to renounce before in the case of sounds?

HYL. I frankly own, Philonous, that it is in vain to longer. Colours, sounds, tastes, in a word all those termed SECONDARY QUALITIES, have certainly no existence without the mind. But by this acknowledgment I must not be supposed to derogate, the reality of Matter, or external objects; seeing it is no more than several philosophers maintain, who nevertheless are the farthest imaginable from denying Matter. For the clearer understanding of this, you must know sensible qualities are by philosophers divided into PRIMARY and SECONDARY. The former are Extension, Figure, Solidity, Gravity, Motion, and Rest; and these they hold exist really in bodies. The latter are those above enumerated; or, briefly, ALL SENSIBLE QUALITIES BESIDE THE PRIMARY; which they assert are only so many sensations or ideas existing nowhere but in the mind. But all this, I doubt not, you are apprised of. For my part, I have been a long time sensible there was such an opinion current among philosophers, but was never thoroughly convinced of its truth until now.

PHIL. You are still then of opinion that EXTENSION and FIGURES are inherent in external unthinking substances?

HYL. I am.

PHIL. But what if the same arguments which are brought against Secondary Qualities will hold good against these also?

HYL. Why then I shall be obliged to think, they too exist only in the mind.

PHIL. Is it your opinion the very figure and extension which you perceive by sense exist in the outward object or material substance? HYL. It is.

PHIL. Have all other animals as good grounds to think the same of the figure and extension which they see and feel?

HYL. Without doubt, if they have any thought at all.

PHIL. Answer me, Hylas. Think you the senses were bestowed upon all animals for their preservation and well-being in life? or were they given to men alone for this end?

HYL. I make no question but they have the same use in all other animals.

PHIL. If so, is it not necessary they should be enabled by them to perceive their own limbs, and those bodies which are capable of harming them?

HYL. Certainly.

PHIL. A mite therefore must be supposed to see his own foot, and things equal or even less than it, as bodies of some considerable dimension; though at the same time they appear to you scarce discernible, or at best as so many visible points?