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.