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thing but powers in it to produce those ideas in us : we also by our senses perceive the colour and brittleness of charcoal, whereby we come by the knowledge of another power in fire, which it has to change the colour and consistency of wood. By the former, fire immediately, by the latter it mediately discovers to us these several qualities, which therefore we look upon to be a part of the qualities of fire, and so make them a part of the complex idea of it. For all those powers that we take cognizance of, terminating only in the alteration of some sensible qualities in those subjects on which they operate, and so making them exhibit to us new sensible ideas; therefore it is that I have reckoned these powers amongst the simple ideas, which make the complex opes of the sorts of substances; though these powers, considered in themselves, are truly complex ideas. And in this looser sense I crave leave to be understood, when I name any of these potentialities amoug the simple ideas, which we recollect in our minds, when we think of particular substances. For the powers that are severally in them are necessary to be considered, if we will have true distinct notions of the several sorts of substances.
§. 8. Nor are we to wonder, that powers make a great part of our complex ideas of And why. substances; since their secondary qualities are those, which in most of them serve principally to distinguisha substances one from another, and commonly make a considerable part of the complex idea of the several sorts of them. For our senses failing us in the discovery of the bulk, texture, and figure of the minute parts of bodies, on which their real constitutions and differences depend, we are fain to make use of their secondary qualities, as the characteristical notes and marks, whereby to frame ideas of them in our minds, and distinguish them one from another. All which secondary qualities
, as has been shown, are nothing but bare powers. For the colour and taste of opium are, as well as its soporifick or anodyne virtues, niere powers depending on its primary qualities, whereby it is
Three sorts of ideas
fitted to produce different operations on different parts of our bodies.
$. 9. The ideas that make our complex
ones of corporeal substances, are of these make our
three sorts. First, the ideas of the primary i complex ones of sub- qualities of things, which are discovered by
our senses, and are in them even when we perceive them not; such are the bulk, figure, number, situation, and motion of the parts of bodies, which are really in them, whether we take notice of them or no. Secondly, the sensible secondary qualities, which depending on these, are nothing but the powers those substànces have to produce several ideas in us by our senses; which ideas are not in the things themselves, otherwise than as any thing is in its cause. Thirdly, the aptness we consider in any substance to give or receive such alterations of primary qualities, as that the substance so altered should produce in us different ideas from what it did before; these are called active and passive powers : all which powers, as far as we have any notice or notion of them, terminate only in sensible simple ideas. For whatever alteration a loadstone has the power to make, in the minute particles of iron, we should have no notion of any power it had at all to operate on iron, did not its sensible motion discover it: and I doubt not, but there are a thousand changes, that bodies we daily handle have a power to cause in one another, which we never suspect, because they never appear in sensible effects. Powers make
§. 10. Powers therefore justly make a a great part great part of our complex ideas of sub
stances. He that will examine his complex plex ideas of idea of gold, will find several of its ideas substances.
that make it up to be only powers : as the power of being melted, but of not spending itself in the fire; of being dissolved in aqua regia ; are ideas as necessary to make up our complex idea of gold, as its colour and weight : which, if duly considered, are also nothing but different powers. For to speak truly, yellowness is not actually in gold; but is a power in gold to produce that idea in us by our eyes, when placed in
of our com
The now se
a due light: and the heat which we cannot leave out of our ideas of the sun, is no more really in the sun, than the white colour it introduces into wax. These are both equally powers in the sun, operating, by the motion and figure of its sensible parts, so on a man, as to make him have the idea of heat; and so on wax, as to make it capable to produce in a man the idea of white.
§. 11. Had we senses acute enough to discern the minute particles of bodies, and condary qua. the real constitution on which their sensible lities of boqualites depend, I doubt not but they dies would would produce quite different ideas in us;
we could disa and that which is now the yellow colour of cover the prigold, would then disappear, and instead of mary ones of it we should see an admirable texture of their minute parts of a certain size and figure. This parts. microscopes plainly discover to us; for what to our naked eyes, produces a certain colour, is, by thus augmenting the acuteness of our senses, discovered to be quite a different thing; and the thus altering, as it were, the proportion of the bulk of the minute parts of à coloured object to our usual sight, produces different ideas froin what it did before. Thius sand or pounded glass, which is opake, and white to the naked eye, is pellucid in a microscope ; and a hair seen this way, loses its former colour, and is in a grent measure pellucid, with a mixture of some bright sparkling colours, such as appear from the refraction of diamonds. and other pellucid bodies. Blood to the naked eye appears all red; but by a good microscope, wherein its lesser parts appear, shows only some few globules of red, swimming in a pellucid liquor: and how these red globules would appear, if glasses could be found that could yet magnify them a thousand or ten thousand times more, is uncertain.
s. 12. The infinitely wise contriver of Our faculties us, and all things about us, hath fitted our
suited to our senses, faculties, and organs, to the conve
state. niencies of life, and the business we have to do here. We are able, by our senses, to know and distinguish things; and to examine them so far, as to
apply them to our uses, and several ways to accom-
the same to him, and others; the visible ideas of every thing would be different. So that I doubt, whether he and the rest of men could discourse concerning the objects of sight, or have any communication about colours, their appearances being so wholly different. And perhaps such a quickness and tenderness of sight could not endure bright sun-shine, or so much as open day-light; nor take in but a very small part of any object at once, and that too only at a very near distance. And if by the help of such microscopical eyes (if I may so call them) a man could penetrate farther than ordinary into the secret composition and radical texture of bodies, he would not make any great advantage by the change, if such an acute sight would not serve to conduct him to the market and exchange; if he could not see things he was to avoid, at a convenient distance; nor distinguish things he had to do with, by those sensible qualities others do. He that was sharp-sighted enough to see the configuration of the minute particles of the spring of a clock, and observe upon what peculiar structure and impulse its elastic motion depends, would no doubt discover something very admirable: but if eyes so framed could not view at once the hand, and the characters of the hourplate, and thereby at a distance see what o'clock it was, their owner could not be much benefited by that acuteness; which, whilst it discovered the secret contrivance of the parts of the machine, made him lose its use. §. 13. And here give me leave to pro
Conjecture pose an extravagant conjecture of mine,
about spirits. viz. that since we have some reason (if there be any credit to be given to the report of things, that our philosophy, cannot account for) to imagine, that spirits ean assume to themselves bodies of different bulk, figure, and conformation of parts; whether one great advantage some of them have over us, may not lie in this, that they can so frame and shape to themselves organs of sensation or perception, as to suit them to their present design, and the circumstances of the object they would consider. For how much would that man exceed all others in knowledge, who had but the VOL. II.