minal effence is kept to, as the boundary of each fpecies, and men extend the application of any general term no farther than to the particular things in which the complex idea it ftands for is to be found, there they are in no danger to mistake the bounds of each Species, nor can be in doubt, on this account, whether any propofition be true or no. 1 have chofe to explain this uncertainty of propofitions in this fcholaftic way, and have made ufe of the terms of effences and Species, on purpose to fhow the abfurdity and inconvenience there is to think of them, as of any other fort of realities, than barely abstract ideas with names to them. To fuppofe that the Species of things are any thing but the forting of them under general names, according as they agree to feveral abstract ideas, of which we make thofe names the figns, is to confound truth, and introduce uncertainty into all general propofitions that can be made about them. Though therefore these things might, to people not poffeffed with fcholaftic learning, be perhaps treated of in a better and clearer way, yet those wrong notions` of effences or fpecies having got root in moft people's minds, who have received any tincture from the learning which has prevailed in this part of the world, are to be discovered and removed, to make way for that ufe of words which fhould convey certainty with it.

§ 5. This more particularly concerns Subftances. THE names of fubftances then, whenever made to fland for fpecies, which are fuppofed to be conftituted by real effences, which we know not, are not capable to convey certainty to the understanding. Of the truth of general propofitions made up of fuch terms, we cannot be fure; the reafon whereof is plain; for how can we be fure that this or that quality is in gold, when we know not what is or is not gold? Since in this way of speaking, nothing is gold but what partakes of an effence, which we not knowing, cannot know where it is or is not, and fo cannot be fure that any parcel of matter in the world is or is not in this fenfe gold; being incurably ignorant, whether it has or has not

that which makes any thing to be called gold, i. e. that real effence of gold whereof we have no idea at all this being as impoffible for us to know, as it is for a blind man to tell in what flower the colour of a panfe is or is not to be found, whilft he has no idea of the colour of a panfie at all. Or if we could (which is impoffible) certainly know where a real effence, which we know not, is; v. g. in what parcels of matter the real effence of gold is; yet could we not be fure, that this or that quality could with truth be affirmed of gold; fince it is impoffible for us to know, that this or that quality or idea has a neceffary connection with a real effence, of which we have no idea at all, whatever fpecies that fuppofed real effence may be imagined to conftitute.

§ 6. The Truth of few univerfal Propofitions concerning Subftances is to be known.

On the other fide, the names of fubftances, when made ufe of, as they fhould be, for the ideas men have in their minds, though they carry a clear and determinate fignification with them, will not yet ferve us to make many univerfal propofitions, of whofe truth we can be certain; not because in this ufe of them we are uncertain what things are fignified by them, but because the complex ideas they stand for, are fuch combinations of fimple ones, as carry not with them any discoverable connection or repugnancy, but with a very few other ideas.

$7. Becaufe co-existence of Ideas in few cafes is to

be known.

THE Complex ideas, that our names of the species of fubftances properly ftand for, are collections of fuch qualities as have been obferved to co-exist in an unknown fubftratum, which we call fubftance: but what other qualities neceffarily co-exist with fuch combinations, we cannot certainly know, unless we can difcover their natural dependence; which in their primary qualities, we can go but a very little way in; and in all their fecondary qualities, we can discover no connection at all, for the reafons mentioned, chap. 3.

viz. 1. Because we know not the real conftitutions of substances, on which each fecondary quality particularly depends. 2. Did we know that, it would ferve us only for experimental (not univerfal) knowledge, and reach with certainty no farther than that bare inftance; because our understandings can difcover no conceivable connection between any fecondary quality, and any modification whatsoever of any of the primary ones. And therefore there are very few general propofitions to be made concerning fubftances, which can carry with them undoubted certainty.

$8. Inftance in Gold.

ALL gold is fixed, is a propofition whofe truth we cannot be certain of, how univerfally foever it be believed. For if, according to the ufelefs imagination of the schools, any one fuppofes the term gold to ftand for a fpecies of things fet out by nature, by a real effence belonging to it, it is evident he knows not what particular fubftances are of that fpecies; and fo cannot, with certainty, affirm any thing univerfally of gold. But if he makes gold ftand for a fpecies determined by its nominal effence, let the nominal effence, for example, be the complex idea of a body of a certain yellow colour, malleable, fufible, and heavier than any other known; in this proper ufe of the word gold, there is no difficulty to know what is or is not gold. But yet no other quality can with certainty be univerfally affirmed or denied of gold, but what hath a difcoverable connection or inconfiftency with that nominal effence. Fixedness, for example,, having no neceffary connection, that we can difcover, with the colour, weight, or any other fimple idea of our complex one, or with the whole combination together, it is impoffible that we should certainly know the truth of this propofition, that all gold is fixed.

$9.

As there is no difcoverable connection between fixednefs, and the colour, weight, and other fimple ideas of that nominal effence of gold; fo if we make our complex idea of gold, a body yellow, fufible, ductile,

weighty, and fixed, we fhall be at the fame uncertainty concerning folubility in aqua regia, and for the fame reafon; fince we can never, from confideration of the ideas themselves, with certainty affirm or deny of a body, whofe complex idea is made up of yellow, very weighty, ductile, fufible, and fixed, that it is foluble in aqua regia, and fo on of the reft of its qualities. I would gladly meet with one general affirmation concerning any quality of gold, that any one can certainly know is true. It will, no doubt, be presently objected, is not this an univerfal eertain propofition, all gold is malleable? To which I anfwer, it is a very certain propofition, if malleableness be a part of the complex idea the word gold ftands for. But then here is nothing affirmed of gold, but that that found ftands for an idea in which malleableness is contained and fuch a fort of truth and certainty as this, it is to fay a centaur is four-footed. But if malleablenefs makes not a part of the fpecific effence the name gold ftands for, it is plain, all gold is malleable, is not a certain propofition; becaufe, let the complex idea of gold be made up of which foever of its other qualities you pleafe, malleableness will not appear to depend on that complex idea, nor follow from any fimple one contained in it; the connection that malleablene/shas (if it has any) with thofe other qualities, being only by the intervention of the real conftitution of its infenfible parts; which, fince we know not, it is impoffible we fhould perceive that connection, unless we could difcover that which ties them together.

:

But

10. As far as any fuch co-existence can be known, fo far univerfal Propofitions may be certain. this will go but a little way, becaufe, THE more, indeed, of thefe co-exifting qualities we unite into one complex idea, under one name, the more precife and determinate we make the fignification of that word; but yet never make it thereby more capable of univerfal certainty, in refpect of other qualities not contained in our complex idea, fince we perceive not their connection or dependence one on

;

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 fubftances, is not, as in other things, barely of the relation of two ideas that may exift feparately, but is of the neceffary connection and co-exiftence of several distinct ideas in the same subject, or of their repugnancy fo to co-exift. 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, fufible, and fixed, and fit to be diffolved in this fort of liquor, and not in another; if (1 fay) we had fuch an idea as this of bodies, and could perceive wherein all fenfible qualities originally confist, and how they are produced, we might frame fuch abstract ideas of them, as would furnith us with matter of more general knowledge, and enable us to make univerfal propofitions, that fhould carry general truth and certainty with them but whilft our complex ideas of the forts of fubftances are fo remote from that internal real constitution on which their fenfible qualities depend, and are made up of nothing but an imperfect collection of those appa rent qualities our fenfes can discover, there can be very few general propofitions concerning fubftances, of whofe real truth we can be certainly affured, fince there are but few fimple ideas, of whofe connection and neceffary co-existence we can have certain and undoubted knowledge. I imagine, amongst all the fecondary qualities of fubftances, and the powers relating to them, there cannot any two be named, whose neceffary co-existence, or repugnance to co-exift, can certainly be known, unless in thofe of the fame fenfe, which neceffarily exclude one another, as I have elfewhere fhowed. No one, I think, by the colour that is in any body, can certainly know what fmell, tafte, found, or tangible qualities it has, nor what alterations it is capable to make or receive on or from other bodies. The fame may be faid of the found or taste, &c. Our fpecific names of fubftances ftanding for