Whatsoever the mind perceives IN ITSELF, or is the immediate object of perception, thought, or understanding, that I call IDEA; and the power to produce any idea in our mind, I call QUALITY of the subject wherein that power is. Thus a snowball having the power to produce in us the ideas of white, cold, and round,—the power to produce those ideas in us, as they are in the snowball, I call qualities; and as they are sensations or perceptions in our understandings, I call them ideas; which IDEAS, if I speak of sometimes as in the things themselves, I would be understood to mean those qualities in the objects which produce them in us.
- Primary Qualities of Bodies.
Concerning these qualities, we, I think, observe these primary ones in bodies that produce simple ideas in us, viz. SOLIDITY, EXTENSION, MOTION or REST, NUMBER or FIGURE. These, which I call ORIGINAL or PRIMARY qualities of body, are wholly inseparable from it; and such as in all the alterations and changes it suffers, all the force can be used upon it, it constantly keeps; and such as sense constantly finds in every particle of matter which has bulk enough to be perceived; and the mind finds inseparable from every particle of matter, though less than to make itself singly be perceived by our senses: v.g. Take a grain of wheat, divide it into two parts; each part has still solidity, extension, figure, and mobility: divide it again, and it retains still the same qualities; and so divide it on, till the parts become insensible; they must retain still each of them all those qualities. For division (which is all that a mill, or pestle, or any other body, does upon another, in reducing it to insensible parts) can never take away either solidity, extension, figure, or mobility from any body, but only makes two or more distinct separate masses of matter, of that which was but one before; all which distinct masses, reckoned as so many distinct bodies, after division, make a certain number.
- [not in early editions]