to Opinion, and has not that Certainty which is requifite to Knowledge. For all general Knowledge lies only in our own Thoughts, and confists barely in the Contemplation of our own abstract Ideas. Wherever we perceive any Agreement or Difagreement 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 Subftances, for which their fpecifick Names stand, whenever they have any distinct and determinate Signification, have a discoverable Connection or Inconfiftency with but a very few other Ideas, the Certainty of univerfal Propofitions concerning Substances, is very narrow and scanty in that Part, which is our principal Enquiry concerning them; and there is scarce any of the Names of Substances, 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.

What is requifite for our Knowledge of Subftances.

§. 14. 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 Senfations or Ideas in us. This is in Truth, no less than to know all the Effects of Matter, under its diverse 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, or Motion of Corpufcles, would produce in us the Sensation of a yellow Colour, and what fort of Figure, Bulk and Texture of Parts in the Superficies of any Body, were fit to give fuch Corpufcles their due Motion to produce that Colour; would that be enough to make universal Propofitions with Certainty, concerning the several forts of them, unless we had Faculties acute enough to perceive the precife Bulk, Figure, Texture and Motion of Bodies in those minute Parts, by which they operate on our Senfes, that fo we might by those frame our abstract Ideas of them. I have mentioned here only corporeal Substances, whofe Operations feem to lie more level to our Understandings: For as to the Operations of Spirits, both their thinking and moving of Bodies, we at firft Sight find ourselves at a lofs; though perhaps, when we have applied our Thoughts a little nearer to the Confideration of Bodies, and their Opera

Whilft our Ideas of SubRances contain

not their real Confiitutions,

but few gene's ral certain Propofitions, concerning them.

we can make

tions and examined how far our Notions, even in thefe, reach, with any Clearnefs, beyond fenfible Matter of Fact, we shall be bound to confefs, that even in these too, our Discoveries amount to very little beyond perfect Ignorance and Incapacity. S. 15. This is evident, the abstract complex Ideas of Subftances, for which their general Names ftand, not comprehending their real Conftitutions, can afford us but very little univerfal Certainty. Because our Ideas of them are not made up of that, on which those Qualities we observe in them, and would inform ourselves about, do depend, or with which they have any certain Connection. V. g. Let the Idea to which we give the Name Man, be, as it commonly is, a Body of the ordinary Shape, with Senfe, voluntary Motion and Reason joined to it. This being the abstract Idea, and confequently the Effence of our Species Man, we can make but very few general certain Propofitions concerning Man, standing for such an Idea. Because not knowing the real Constitution on which Sensation, Power of Motion and Reasoning, with that peculiar Shape, depend, and whereby they are united together in the same Subject, there are very few other Qualities, with which we can perceive them to have a neceffary Connection; and therefore we cannot with Certainty affirm, That all Men fleep by Intervals; that no Man can be nourifhed by Wood or Stones: that all Men will be poisoned by Hemlock : Because these Ideas have no Connection, nor Repugnancy with this our nominal Effence of Man, with this abftract Idea that Name stands for. We must in these and the like appeal to Trial in particular Subjects, which can reach but a little way. We must content ourselves with Probability in the reft; but can have no general Certainty, whilst our Specifick Idea of Man contains not that real Constitution which is the Root wherein all his infeparable Qualities are united, and from whence they flow. Whilft our Idea the Word Man stands for, is only an imperfect Collection of some fenfible Qualities and Powers in him, there is no difcernable Connection or Repug→ nance between our Specifick Idea, and the Operation of either the Parts of Hemlock or Stones, upon his Constitution. There are Animals that fafely eat Hemlock, and others that are nourished by Wood and Stones: But as long as we want Ideas of those real Constitutions of different sorts of Animals, whereon these, and the like Qualities and Powers depend, we must not hope to reach Certainty in univerfal Propofitions concerning them.

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Those

Thole ew Ideas only, which have a discernible Connection with our nominal Effence, or any part of it, can afford us fuch Propofitions. But these are so few, and of fo little Moment, that we may juftly look on our certain general Knowledge of Subftances, as almost none at all.

Wherein lies the general Certainty of Propofitions.

§. 16. To conclude, General Propofitions, of what kind foever, are then only capable of Gertainty, when the Terms used in them stand for fuch Ideas, whofe Agreement or Difagreement, as there expreffed, is capable to be discovered by us. And we are then certain of their Truth or Falfhood, when we perceive the Ideas the Terms ftand for, to agree, or not agree, according as they are affirmed or denied one of another. Whence we may take Notice, that general Certainty is never to be found but in our Ideas. Whenever we go to seek it elsewhere in Experiment or Obfervations without us, our Knowledge goes not beyond Particulars. It is the Contemplation of our own abstract Ideas, that alone is able to afford us general Knowledge.

They are Jelf-evident.

CHAP. VII.

Of Maxims.

HERE are a fort of Propofitions, which under the Name of Maxims and Axioms, have paffed for Principles of Science; and because they are felf-evident, have been fuppofed innate, although no body (that I know) ever went about to fhew the Reason and Foundation of their Clearness and Cogency. It may however be worth while to enquire into the Reason of their Evidence, and see whether it be peculiar to them alone, and also examine how far they influence and govern our other Knowledge.

Wherein that Self-evidence

confifts.

§. 2. Knowledge, as has been fhewn, confifts in the Perceptions of the Agreement or Difagreement of Ideas: Now, where that Agreement or Difagreement is perceived immediately by itself, without the Intervention or Help of any tother, here our Knowledge is felf-evident. This will appear to be fo to any one, who will but confider any of thofe Propofitions, which, without any Proof, he affents to at first Sight; for in all of them he will find, that the Reafon of his Affent, is from that Agreement or Difagreement, which the Mind, by an immediate comparing them,

finds in those Ideas answering the Affirmation or Negation in the Propofition.

Self-evidence not peculiar to

received Axi

oms.

Firf, As to Identity and Diversity, all Propofitions are equally self-evi

dent.

S. 3. This being fo, in the next Place let us confider, whether this Self-evidence be peculiar only to those Propofitions which commonly pass under the Names of Maxims, and have the Dignity of Axioms allowed them. And here it is plain, that several other Truths, not allowed to be Axioms, partake equally with them in this Self-evidence. This we fhall fee, if we go over these several forts of Agreement or Disagreement of Ideas, which I have above-mentioned, viz. Inentity, Relation, Co-existence, and real Exiftence; which will difcover to us, that not only those few Propofitions, which have had the Credit of Maxims, are felf-evident, but a great many, even almost an infinite Number of other Propofitions are fuch. 6. 4. For First, The immediate Perception of the Agreement or Disagreement of Identity, being founded in the Mind's having diftinct Ideas, this affords us as many Self-evident Propofitions, as we have distinct Ideas. Every one that has any Knowledge at all, has, as the Foundation of it, various and diftinct Ideas: And it is the first Act of the Mind, (without which, it can never be capable of any Knowledge) to know every one of its Ideas by itself, and diftinguish it from others. Every one finds in himself, that he knows the Ideas he has; that he knows also, when any one is in his Understanding, and what it is; and that when more than one are there, he knows them distinctly and unconfusedly one from another. Which always being fo, (it being impoffible but that he should perceive what he perceives) he can never be in doubt when any Idea is in his Mind, that it is there, and is that Idea it is; and that two diftinct Ideas, when they are in his Mind, are there, and are not one and the fame Idea.. So that all fuch Affirmations and Negations, are made, without any Poffibility of Doubt, Uncertainty or Hefitation, and must neceffarily be affented to, as soon as understood; that is, as soon as we have in our Minds, determined Ideas, which the Terms in the Propofition ftand for. And therefore wherever the Mind with Attention confiders any Propofition, so as to perceive the two Ideas, fignified by the Terms, and affirmed or denied one of the other, to be the fame or different, it is presently and infallibly certain of the Truth of fuch a Propofition, and this equally, whether these Propofitions be in Terms standing for more general Ideas, or fuch as are lefs fo, v. g. whether

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the

the general Idea of Being be affirmed of itfelf, as in this Propofition, Whatsoever is, is; or a more particular Idea be affirmed of itself, as a Man is a Man, or whatsoever is White, is White. Or whether the Idea of Being in general be denied of not Being, which is the only (if I may fo call it) Idea different from it, as in this other Propofition, it is impoffible for the fame Thing to be, and not to be; or any Idea of any particular Being be denied of another different from it, as a Man is not a Horfe; Red is not Blue. The Difference of the Ideas, as foon as the Terms are understood, makes the Truth of the Propofition presently visible, and that with an equal Certainty and Eafinefs in the lefs, as well as the more general Propofitions, and all for the fame Reafon, viz. because the Mind perceives in any Ideas, that it has the fame Idea to be the fame with itself; and two different Ideas to be different, and not the fame. And this it is equally certain of, whether these Ideas be more or less general, abstract, and comprehenfive. It is not therefore alone to thefe two general Propofitions, Whatfoever is, is; and it is impossible for the fame Thing to be, and not to be; that this Self-evidence belongs by any peculiar Right. The Perception of being, or not being, belongs no more to these vague Ideas, fignified by the Terms Whatsoever and Thing, than it does to any other Ideas, These two general Maxims amounting to no more, in short, but this, that the fame is the fame, and fame is not different, are Truths known in more particular Inftances, as well as in these general Maxims, and known alfo in particular Inftances, before thefe general Maxims are ever thought on, and draw all their Force from the Discernment of the Mind employed about particular Ideas. There is nothing more visible, than that the Mind, without the help of any Proof or Reflection on either of these general Propofitions, perceives fo clearly, and knows fo certainly, that the Idea of White is the Idea of White, and not the Idea of Blue; and that the idea of White, when it is in the Mind, is there, and is not abfent, that the Confideration of thefe Axioms can add nothing to the Evidence or Certainty of its Knowledge. Juft fo it is (as every one may experiment in himself) in all the Ideas a Man has in his Mind:" He knows each to be itself, and not to be another; and to be in his Mind, and not away, when it is there, with a Certainty that cannot be greater; and therefore the Truth of no general Propofition can be known with a greater Certainty, nor add any thing to this. So that in refpect of Identity, our intuitive Knowledge reaches as far as our Ideas. And we are capable of making as

many