not know that any parcel of matter, with another par cel of matter joined to it, is bigger than either of them alone, will never be able to know it by the help of these two relative terms, whole and part, make of them what maxim you please.

§ 4. Dangerous to build upon precarious Principles. Bur be it in the mathematics as it will, whether it be clearer, that taking an inch from a black line of two inches, and an inch from a red line of two inches, the remaining parts of the two lines will be equal, or that if you take equals from equals, the remainder will be equals; which, I fay, of these two is the clearer and first known, I leave to any one to determine, it not being material to my prefent occafion. That which I have here to do is to inquire, whether, if it be the readiest way to knowledge to begin with general maxims, and build upon them, it be yet a safe way to take the principles which are laid down in any other fcience as unquestionable truths, and fo receive them without examination, and adhere to them, without fuffering to be doubted of, becaufe mathematicians. have been so happy, or so fair, to use none but selfevident and undeniable. If this be fo, I know not what may not pass for truth in morality, what may not be introduced and proved in natural philofophy.

Let that principle of fome of the philofophers, that all is matter, and that there is nothing elfe, be received for certain and indubitable, and it will be eafy to be seen by the writings of fome that have revived it again in our days, what confequences it will lead us into. Let any one, with Polemo, take the world, or with the floics, the ether or the fun, or with Anaximenes, the air, to be God; and what a divinity, religion and worship must we needs have! Nothing can be fo dangerous as principles thus taken up without queftioning or examination, especially if they be fuch as concern morality, which influence mens lives, and give a bias to all their actions. Who might not juftly expect another kind of life in Aristippus, who placed happiness in bodily pleasure, and in Antifthenes, who

Book IV. made virtue fufficient to felicity? And he who, with Plato, fhall place beatitude in the knowledge of God, will have his thoughts raised to other contemplations than those who looked not beyond this spot of earth, aud those perishing things which are to be had in it. He that with Archelaus fhall lay it down as a principle, that right and wrong, honest and difhoneft, are defined only by laws, and not by nature, will have other measures of moral rectitude and pravity than those who take it for granted that we are under obligations antecedent to all human conftitutions.

$5. This is no certain way to Truth.

IF, therefore, those that pass for principles, are not certain (which we must have fome way to know, that we may be able to diftinguish them from thofe that are doubtful), but are only made fo to us by our blind afsent, we are liable to be misled by them, and instead of being guided into truth, we fhall by principles be only confirmed in mistake and error.

§ 6. But to compare clear complete Ideas under Ready Names.

Bur fince the knowledge of the certainty of principles, as well as of all other truths, depends only upon the perception we have of the agreement or difagreement of our ideas, the way to improve our knowledge is not, I am fure, blindly, and with an implicit faith, to receive and swallow principles; but is, I think, to get and fix in our minds clear, diftinct and complete ideas, as far as they are to be had, and annex to them proper and conftant names; and thus, perhaps, without any other principles, but barely confidering thofe ideas, and by comparing them one with another, finding their agreement and disagreement, and their feveral relations and habitudes, we fhall get more true and clear knowledge, by the conduct of this one rule, than by taking up principles, and thereby putting our minds into the difpofal of others.

§ 7. The true Method of advancing Knowledge is by confidering our abftract Ideas.

WE must therefore, if we will proceed as reafon adviles, adapt our methods of inquiry to the nature of the ideas we examine, and the truth we fearch after. General and certain truths are only founded in the habitudes and relations of abftract ideas. A fagacious and methodical application of our thoughts, for the finding out these relations, is the only way to discover all that can be put, with truth and certainty, concerning them, into general propofitions. By what fteps we are to proceed in thefe, is to be learned in the schools of the mathematicians, who from very plain and eafy beginnings, by gentle degrees, and a continued chain of reasonings, proceed to the difcovery and demonftration of truths, that appear at first fight beyond human capacity. The art of finding proofs, and the admirable methods they have invented for the fingling out and laying in order those intermediate ideas, that demonftratively fhow the equality or inequality of unapplicable quantities, is that which has carried them fo far, and produced fuch wonderful and unexpected difcoveries; but whether fomething like this, in respect of other ideas, as well as thofe of magnitude, may not in time be found out, I will not determine. This I think I may fay, that if other ideas, that are the real as well as the nominal effences of their fpecies, were purfued in the way familiar to mathematicians, they would carry our thoughts farther, and with greater evidence and clearnefs, than poffibly we are apt to imagine.

§ 8. By which Morality also may be made clearer. THIS gave me the confidence to advance that conjecture, which I fuggeft, chap. 3. viz. that morality is capable of demonstration as well as mathematics; for the ideas that ethics are converfant about being all' real effences, and fuch as I imagine have a difcoverable connection and agreement one with another; fo far as we can find their habitudes and relations, so far we shall be poffeffed of certain, real and general

Book IV. truths; and I doubt not, but if a right method were taken, a great part of morality might be made out with that clearness that could leave to a confidering man no more reafon to doubt, than he could have to doubt of the truth of propofitions in mathematics, which have been demonftrated to him.

$9. But Knowledge of Bodies is to be improved only by Experience.

IN our fearch after the knowledge of fubftances, our want of ideas that are fuitable to fuch a way of proceeding, obliges us to a quite different method. We advance not here as in the other (where our abstract ideas are real as well as nominal effences), by contemplating our ideas, and confidering their relations and correfpondences; that helps us very little, for the reafons that in another place we have at large fet down. By which I think it is evident, that fubftances afford matter of very little general knowledge, and the bare contemplation of their abstract ideas will carry us but a very little way in the fearch of truth and certainty. What then are we to do for the improvement of our knowledge in fubftantial beings? Here we are to take a quite contrary courfe; the want of ideas of their real effences fends us from our own thoughts to the things themselves as they exift: Experience bere muft teach me what reafon cannot, and it is by trying alone that I can certainly know what other qualities co-exist with thofe of my complex idea, v. g. whether that yellow, heavy, fufible body I call gold be malleable or no, which experience (which way ever it prove in that particular body I examine) makes me not certain that it is fo in all, or any other yellow, heavy, fufible bodies, but that which I have tried; because it is no confequence one way or the other from my complex idea; the neceffity or inconfiftence of malleability hath no visible connection with the combination of that colour, weight, and fufibility in any body. What I have faid here of the nominal effence of geld, fuppofed to confift of a body of fuch a determinate colour, weight and fufibility,

139 will hold true, if malleableness, fixedness, and folubility in aqua regia be added to it. Our reafonings from these ideas will carry us but a little way in the certain discovery of the other properties in those mafles of matter wherein all thefe are to be found; because the other properties of fuch bodies depending not on these, but on that unknown real effence, on which these alfo depend, we cannot by them difcover the reft; we can go no farther than the fimple ideas of our nominal effence will carry us, which is very little beyond themselves, and fo afford us but very fparingly any certain univerfal and useful truths; for upon trial having found that particular piece (and all others of that colour, weight and fufibility that I ever tried) malleable, that also makes now perhaps a part of my complex idea, part of my nominal effence of gold; whereby, though I make my complex idea to which I affix the name gold, to confist of more fimple ideas than before, yet ftill, it not containing the real effence of any fpecies of bodies, it helps me not certainly to know (I fay to know, perhaps it may to conjecture) the other remaining properties of that body, farther than they have a visible connection with fome or all of the fimple ideas that make up my nominal effence. For example, I cannot be certain from this complex idea, whether gold be fixed, or no; because, as before, there is no neceffary connection or inconfiftence to be difcovered betwixt a complex idea of a body, yellow, heavy, fufible, malleable; betwixt thefe, I fay, and fixednefs; so that I may certainly know, that in whatsoever body these are found, there fixednefs is fure to be. Here again for affurance, I must apply myself to experience; as far as that reaches, I may have certain knowledge, but no farther.

$10. This may procure us Convenience, not Science. I DENY not but a man, accustomed to rational and regular experiments, shall be able to fee farther into the nature of bodies, and guess righter at their yet unknown properties, than one that is a stranger to them; but yet, as I have said, this is but judgment and opi