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any collections of fuch ideas, it is not to be wondered, that we can with them make very few general propofitions of undoubted real certainty; but yet fo far as any complex idea of any fort of fubftances contains in it any fimple idea, whofe neceffary co-existence with any other may be difcovered, fo far univerfal propofitions may with certainty be made concerning it; v. g. could any one discover a neceffary 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 univerfal propofition concerning gold in this refpect; 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.

11. The Qualities which make our complex Ideas of Subftances depend mostly on external, remote, and unperceived Caufes.

HAD we fuch ideas of fubftances, as to know what real constitutions produce thofe fenfible qualities we find in them, and how thofe qualities flowed from thence, we could by the specific ideas of their real effences in our own minds, more certainly find out their properties, and difcover what qualities they had or had not, than we can now by our fenses; and to know the properties of gold, it would be no more neceffary that gold fhould exift, and that we should make experiments upon it, than it is neceffary for the knowing the properties of a triangle, that a triangle should exift in any matter; the idea in our minds would ferve for the one as well as the other; but we are fo far from being admitted into the fecrets of Nature, that we scarce fo much as ever approach the first entrance towards them; for we are wont to confider the fubftances we meet with each of them as an entire thing by itself, having all its qualities in itself, and independent of other things; overlooking, for the most part, the operations of thofe invifible fluids they are encompaffed with, aud upon whose motions and operations depend the greatest part of thofe 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, feparate from the reach and influence of all other bodies, it will immediately lofe 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 effential quality, left to itself, would ceafe to be fluid; but if inanimate bodies owe so much of their present state 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 feeds, in a conftant fucceffion; and if we look a little nearer into the state of animals, we shall find that their dependence, as to life, motion, and the most confiderable qualities to be observed in them, is fo wholly on extrinfical caufes and qualities of other bodies that make no part of them, that they cannot fubfift a moment without them; 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 prefently lofe fenfe, life, and motion. This the neceffity of breathing has forced into our knowledge; but how many other extrinsical, and poffibly very remote bodies, do the fprings of those admirable machines depend on, which are not vulgarly obferved, or fo much as thought on; and how many are there, which the fevereft inquiry can never difcover? The inhabitants of this spot of the universe, though removed fo many millions of miles from the fun, yet depend fo much on the duly tempered motion of particles coming from or agitated by it, that were this earth removed but a fmall part of that distance out of its prefent fituation, and placed a little farther or nearer that source of heat, it is more than probable that the greatest part of the animals in it would immediately perish; fince

we find them fo often destroyed by an excefs or defect of the fun's warmth, which an accidental pofition in fome parts of this our little globe exposes them to. The qualities observed in a loadstone must needs have their fource far beyond the confines of that body; and the ravage made often on several forts of animals, by invifible caufes, 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 neighbouring country, evidently fhow that the concurrence and operation of several bodies, with which they are feldom thought to have any thing to do, is abfolutely neceffary 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 fearch for that conftitution within the body of a fly, or an elephant, upon which depend thofe qualities and powers we obferve in them; for which, perhaps, to understand them aright, we ought to look not only beyond this our earth and atmosphere, but even beyond the fun, or remoteft ftar our eyes have yet difcovered; for how much the being and operation of particular fubftances in this our globe depend on caufes utterly beyond our view, is impoffible for us to determine. We fee and perceive fome of the motions and groffer operations of things here about us, but whence the ftreams 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 fo fay, of this ftupendous structure of the univerfe, may, for ought we know, have fuch a connection and dependence in their influences and operations one upon another, that perhaps things in this our manfion would put on quite another face, and ceafe to be what they are, if fome one of the ftars or great bodies incomprehenfibly remote from us, fhould ceafe to be or move as it does. This is certain; things, however

abfolute and entire they feem in themfelves, are but retainers to other parts of nature, for that which they are most taken notice of by us. Their obfervable qualities, actions, and powers, are owing to fomething without them; and there is not fo complete and perfect 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 furface of any body, but look a great deal farther, to comprehend perfectly thofe qualities that are in it.

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IF this be fo, it is not to be wondered that we have very imperfect ideas of fubftances; and that the real effences, on which depend their properties and operations, are unknown to us. We cannot discover fo much as that size, figure, and texture of their minute and active parts, which is really in them, much less the different motions and impulfes made in and upon them by bodies from without, upon which depends, and by which is formed, the greatest and most remarkable part of thofe qualities we obferve in them, and of which our complex ideas of them are made up. This confideration alone is enough to put an end to all our hopes of ever having the ideas of their real effences; which, whilft we want, the nominal effences we make use of instead of them, will be able to furnifh us but very fparingly with any general knowledge, or univerfal propofitions capable of real certainty.

13. Judgment may reach farther, but that is not

Knowledge.

WE are not therefore to wonder, if certainty be to be found in very few general propofitions made concerning fubftances: Our knowledge of their qualities and properties go very feldom farther than our fenses reach and inform us. Poffibly inquifitive and obferving men may, by ftrength of judgment, penetrate farther, and on probabilities taken from wary obfervation, and hints well laid together, often guefs right at what experience has not yet difcovered to them; But VOL. III.

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Book IV. this is but gueffing ftill; it amounts only to opinion, and has not that certainty which is requifite to know. ledge; for all general knowledge lies only in our own thoughts, and confifts barely in the contemplation of our own abstract ideas. Wherever we perceive any agreement or disagreement amongst them, there we have general knowledge; and by putting the names of thofe ideas together accordingly in propofitions, can with certainty pronounce general truths. But because the abstract ideas of fubftances, for which their specific names ftand, whenever they have any distinct and determinate fignification, have a difcoverable connection or inconfiftency with but a very few other ideas; the certainty of universal propofitions concerning fubStances is very narrow and fcanty in that part, which is our principal inquiry concerning them; and there is fcarce any of the names of fubftances, let the idea it is applied to be what it will, of which we can generally and with certainty pronounce, that it has or has not this or that other quality belonging to it, and conftantly co-existing or inconfiftent with that idea, wherever it is to be found.

§14. What is requifite for our Knowledge of SubStances.

BEFORE We can have any tolerable knowledge of this kind, we must first know what changes the primary qualities of one body do regularly produce in the primary qualities of another, and how. Secondly, We must know what primary qualities of any body produce certain fenfations or ideas in us. This is in truth no less than to know all the effects of matter, under its divers modifications of bulk, figure, cohesion of parts, motion, and reft; which, I think, every body will allow is utterly impoffible to be known by us without revelation; nor, if it were revealed to us what fort of figure, bulk, and motion of corpufcles, would produce in us the fenfation of a yellow colour, and what fort of figure, bulk, and texture of parts, in the fuperficies of any body, were fit to give fuch corpufcles their due motion to produce that colour;

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