II.—Of Idea-Producing Qualities
The power to produce any idea in our mind I call Quality of the subject wherein that power is. Qualities are, first, such as are utterly inseparable from the body in what state soever it be. These I call original or primary qualities, which I think we may observe to produce simple ideas in us, viz., solidity, extension, figure, motion or rest, and number.
Secondly, such qualities which in truth are nothing in the objects themselves, but powers to produce various sensations in us by their primary qualities, i.e., by the bulk, figure, texture, and motion of their insensible parts. These secondary qualities are colours, sounds, tastes, etc. From whence I think it is easy to draw this observation: that the ideas of primary qualities of bodies are resemblances of them, but the ideas produced in us by the secondary qualities have no resemblance in them at all.
If anyone will consider that the same fire that at one distance produces in us the sensation of warmth does, at a nearer approach, produce in us the far different sensation of pain, let him bethink himself what reason he has to say that his idea of warmth, which was produced in him by fire, is actually in the fire; and his idea of pain which the same fire produced in him in the same way, is not in the fire. The particular bulk, number, figure, and motion of the parts of fire or snow are really in them, whether anyone's senses perceive them or not; and, therefore, they may be called real qualities, because they really exist in those bodies. But light, heat, whiteness, or coldness are no more really in them than sickness or pain is in manna. Take away the sensation of them; let not the eyes see light or colours, nor the ears hear sounds; let the palate not taste, nor the nose smell; and all colours, tastes, odours, and sounds, as they are such particular ideas, vanish and cease, and are reduced to their causes, i.e., bulk, figure, and motion of parts.
III.—Various Faculties of the Mind
What perception is everyone will know better by reflecting on what he does himself when he sees, hears, feels, etc., or thinks, than by any discourse of mine. This is certain, that whatever alterations are made in the body, if they reach not the mind, whatever impressions are made on the outward parts, if they are not taken notice of within, there is no perception.
We ought further to consider concerning perception, that the ideas we receive by sensation are often in grown people altered by the judgment without our taking any notice of it. When we set before our eyes a round globe of any uniform colour—e.g., gold, alabaster, or jet—it is certain that the idea thereby imprinted in our mind is of a flat circle variously shadowed with several degrees of light and brightness coming to our eyes. But we having by use been accustomed to perceive what kind of appearances convex bodies are wont to make in us, what alterations are made in the reflections of light by the difference of the sensible figures of bodies, the judgment presently, by an habitual custom, alters the appearances into their causes; so that from that which is truly a variety of shadow or colour collecting the figure, it makes it pass for a mark of figure, and frames to itself the perception of a convex figure and a uniform colour, when the idea we receive from thence is only a plane variously coloured, as is evident in painting. Perception, then, is the first operation of our intellectual faculties, and the inlet of all knowledge into our minds.
The next faculty of the mind whereby it makes a further progress towards knowledge is that which I call Retention, or the keeping of those simple ideas which from sensation or reflection it hath received. This is done, first, by keeping the idea which is brought into it for some time actually in view, which is called Contemplation. The other way of retention is the power to revive again in our minds those ideas which after imprinting have disappeared, or have been, as it were, laid aside out of sight; and thus we do when we conceive heat or light, yellow or sweet, the object being removed. This is memory, which is, as it were, the storehouse of our ideas.
Another faculty we may take notice of in our minds is that of Discerning, and distinguishing between the several ideas it has. It is not enough to have a confused perception of something in general. Unless the mind had a distinct perception of different objects and their qualities, it would be capable of very little knowledge, though the bodies that affect us were as busy about us as they are now, and the mind were continually employed in thinking. On this faculty of distinguishing one thing from another depends the evidence and certainty of several even very general propositions which have passed for innate truths, because men, overlooking the true cause why those propositions find universal assent, impute it wholly to native uniform impressions; whereas it, in truth, depends upon this clear discerning faculty of the mind, whereby it perceives two ideas to be the same or different.
The comparing of ideas one with another is the operation of the mind upon which depends all that large tribe of ideas comprehended under relations. The next operation is composition, whereby the mind puts together several simple ideas and combines them into complex ones.