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another, being ignorant both of that real constitution in which they are all founded, and also how they flow from it ; for the chief part of our knowledge concerning substances, is not, as in other things, barely of the relation of two ideas that may exist separately, but is of the necessary connection and co-existence of feveral diftinct ideas in the same subject, or of their repugnancy so to co-exist. Could we begin at the other end, and discover what it was wherein that colour confifted, what made a body lighter or heavier, what texture of parts made it malleable, fusible, and fixed, and fit to be dissolved in this sort of liquor, and not in another ; if (1 say) we had such an idea as this of bodies, and could perceive wherein all sensible qua. lities originally consilt, and how they are produced, we might frame such abstract ideas of them, as would furnith us with matter of more general knowledge, and enable us to make universal propositions, that should carry general truth and certainty with them; but whilst our complex ideas of the sorts of substances are so remote from that internal real constitution on which their sensible qualities depend, and are made up of nothing but an imperfect collection of those apparent qualities our senses can discover, there can be very few general propositions concerning substances, of whole real truth we can be certainly assured, since there are but few simple ideas, of whose connection and necessary co-existence we can have certain and un. doubted knowledge. I imagine, amongst all the fe. condary qualities of substances, and the powers relate ing to them, there cannot any two be named, whose necessary co-existence, or repugnance to co-exist, can certainly be known, unless in those of the same sense, which necessarily exclude one another, as I have else. where Thowed. No one, I think, by the colour that is in any body, can certainly know what smell, taste, found, or tangible qualities it has, nor what alterations it is capable to make or receive on or from other bodies. The same may be said of the found or taste, &c. Our specific names of substances ftanding for any collections of such ideas, it is not to be wondered, that we can with thein make very few general pro. positions of undoubted recl certainty ; but yet so far as any complex idea of any sort of substances contains in it any simple idea, whose necessary co-exiftence with any other may be discovered, so far universal propofitions may with certainty be made concerning it; v. g. could any one discover a necessary connection between malleableness and the colour or weight of gold, or any other part of the complex idea fignified by that name, he might make a certain universal propofition concerning gold in this respect ; and the real truth of this propofition, that all gold is malleable, would be as certain as of this, the three angles of all right lined triangles are equal to two right ones.
II.' The Qualities which make our complex Ideas of Substances depend moftly on external, remote,
and unperceived Causos. HAD we such ideas of substances, as to know what real constitutions produce those sensible qualities we find in them, and how those qualities flowed from thence, we could by the specific ideas of their real ellences in our own minds, more certainly find out their properties, and discover what qualities they had or had not, than we can now by our senses ; and to know the properties of gold, it would be no more ne. cessary that gold should exist, and that we should make experiments upon it, than it is necessary for the knowing the properties of a triangle, that a triangle fhould exist in any matter ; the idea in our minds would serve for the one as well as the other ; but we are so far from being admitted into the secrets of Nature, that we scarce so much as ever approach the first en. trance towards them ; for we are wont to consider the substances we meet with each of them as an entire thing by itself, having all its qualities in itself, and in. dependent of other things; overlooking, for the inost part, the operations of those invisible fluids tlicy are encompassed with, aud upon whose motions and ope. rations depend the greatest part of those qualities
which are taken notice of in them, and are made by us the inherent marks of distinction whereby we know and denominate them. Put a piece of gold any where by itself, separate from the reach and influence of all other bodies, it will immediately lose all its colour and weight, and perhaps malleableness too ; which, for ought I know, would be changed into perfect friability. Water, in which to us fluidity is an essential quality, left to itself, would cease to be fluid; but if inanimate bodies owe so much of their present ftate to other bodies without them, that they would not be what they appear to us, were those bodies that environ them removed, it is yet more so in vegetables, which are nourished, grow, and produce leaves, flowers and seeds, in a constant succession ; and if we look a little nearer into the state of animals, we shall find that their dependence, as to life, motion, and the molt conliderable qualities to be observed in them, is so wholly on extrinsical causes and qualities of other bodies that make no part of them, that they cannot sublist a moment without thein ; though yet those bodies on which they depend are little taken notice of, and make no part of the complex ideas we frame of those animals. Take the air but a minute from the greatest part of living creatures, and they presently lose fense, life, and motion. This the necellity of breathing has forced into our knowledge ; but how many other extrinsical, and possibiy very remote bodies, do the springs of those admirable machines depend on, which are not vulgarly observed, or so much as thought on; and how many are there, which the severest inquiry can never discover? The inhabitants of this spot of the universe, though removed so many millions of miles from the sun, yet depend so much on the duly tempered motion of particles coming from or agitated by it, that were this earth removed but à : small part of that distance out of its present situation, and placed a little farther or nearer that source of heat, it is more than probable that the greateit part of the aniinals in it would immediately perilh ; hince
we find them so often deftroyed by an excess or defect of the sun's warmth, which an accidental position in some parts of this our little globe exposes them to. The qualities observed in a loadstone must needs have their source far beyond the confines of that body ; and the ravage made often on several sorts of animals, by invisible causes, the certain death (as we are told) of some of them, by barely passing the line, or, as it is certain of others, by being removed into a neighbour. ing country, evidently show that the concurrence and operation of several bodies, with which they are fel. dom thought to have any thing to do, is absolutely necessary to make them be what they appear to us, and to preserve those qualities by which we know and diftinguish them. We are then quite out of the way, when we think that things contain within themselves the qualities that appear to us in them; and we in vain search for that constitution within the body of a Ay, or an elephant, upon which depend those qualities and powers we observe in them ; for which, per. haps, to understand them aright, we ought to look not only beyond this our earth and atmosphere, but even beyond the sun, or remoteft ftar our eyes have yet discovered ; for how much the being and operation of particular substances in this our globe depend on causes utterly beyond our view, is imposible for us to determine. We fee and perceive some of the notions and grosser operations of things here about us, but whence the streams come that keep all these curious machines in motion and repair, how conveyed and modified, is beyond our notice and apprehenfion; and the great parts and wheels, as I may to say, of this stupendous structure of the universe, may, for ought we know, have such a connection and de. pendence in their influences and operations one upon another, that perhaps things in this our mansion would put on quite another face, and cease to be what they are, if some one of the stars or great bodies incomprehensibly remote from us, thould cease to be or move as it does. This is certain ; things, however
absolute and entire they seem in themselves, are but retainers to other parts of nature, for that which they are most taken notice of by us. Their observable qualities, actions, and powers, are owing to something without them; and there is not so complete and perfeat a part that we know of nature, which does not owe the being it has, and the excellencies of it, to its neighbours ; and we must not confine our thoughts within the surface of any body, but look a great deal farther, to comprehend perfectly those qualities that are in it.
$ 12. If this be fo, it is not to be wondered that we have very imperfe&t ideas of fubstances ; and that the real esfences, on which depend their properties and opera. tions, are unknown to us. We cannot discover so much as that size, figure, and texture of their minute and active parts, which is really in them, much less the different motions and impulses made in and upon them by bodies from without, upon which depends, and by which is formed, the greatest and most remarkable part of those qualities we observe in them, and of which our complex ideas of them are made up. This consideration alone is enough to put an end to all our hopes of ever having the ideas of their real essences; which, whilst we want, the nominal effences we make use of instead of them, will be able to fura nish us but very sparingly with any general knowledge, or universal propofitions capable of real certainly. § 13. Judgment may reach farther, but that is 1100 :
. Knowledge. We are not therefore to wonder, if certainty be to be found in very few general propositions made concerning substances : Our knowledge of their qualities and properties go very seldom farther than our senses reach and inform us. Possibly inquisitive and observing men may, by strength of judgment, penetrate farther, and on probabilities taken from wary observation, and hints well laid together, often guess right at what experience has not yet discovered to them : But