may say, that if other ideas, that are the real as well as nominal essences of their species, were pursued in the way familiar to mathematicians, they would carry our thoughts farther, and with greater evidence and clearness, than possibly 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 suggest, chap. 3. viz. "That morality is capable of demonstration, as well as mathematics." For the ideas that ethics are conversant about, being all real essences, and such as, I imagine, have a discoverable connexion and agreement one with another; so far as we can find their habitudes and relations, so far we shall be possessed of certain, real, and general 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 considering man, no more reason to doubt, than he could have to doubt of the truth of propositions in mathematics, which have been demonstrated to him. § 9. But knowledge of bodies is to be improved only by experience. -In our search after the knowledge of substances, our want of ideas, that are suitable to such 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, essences), by contemplating our ideas, and considering their relations and correspondencies; that helps us very little, for the reasons that in another place we have at large set down. By which, I think, it is evident, that substances 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 search of truth and certainty. What then are we to do for the improvement of our knowledge in substantial beings? Here we are to take a quite contrary course; the want of ideas of their real essences, sends us from our own thoughts, to the things themselves, as they exist. Experience here must teach me what reason cannot; and it is by trying alone, that I can certainly know what other qualities co-exist with those of my complex idea, v. g. whether that yellow, heavy, fusible 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 so in all or any other yellow, heavy, fusible bodies, but that which I have tried. Because it is no consequence one way or the other, from my complex idea the necessity of inconsistence of malleability hath no visible connexion with the combination of that colour, weight, and fusibility, in any body. What I have said here of the nominal essence of gold, supposed to consist of a body of such a determinate colour, weight, and fusibility, will hold true, if malleableness, fixedness, and solubility in aqua regia, be added to it. Our reasonings from these ideas will carry us but a little way in the certain discovery of the other properties in those masses of matter, wherein all these are to be found. Because the other properties of such bodies depending not on these, but on that unknown real essence, on which these also depend, we cannot by them discover the rest; we can go no farther than the simple ideas of our nominal essence will carry us, which is very little beyond themselves: and so afford us but very sparingly any certain universal, and useful truths. For upon trial, having found that particular piece (and all others of that colour, weight, and fusibility, that I ever tried) malleable, that also makes now, perhaps, a part of my complex idea, part of my nominal essence, of gold; whereby, though I make my complex idea, to which I affix the name gold, to consist of more simple ideas than before; yet still it not containing the real essence of any species of bodies, it helps me not certainly to know (I say to know, perhaps it may to conjecture) the other remaining properties of that body, farther than they have a visible connexion with some or all of the simple ideas that make up my nominal essence. For example; I cannot be certain from this complex idea, whether gold be fixed or no; because, as before, there is no necessary connexion or inconsistence to be discovered betwixt a complex idea of a body yellow, heavy, fusible, malleable, betwixt these, I say, and fixedness; so that I may certainly know, that in whatsoever body these are found, there fixedness is sure to be. Here again, for assurance, 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 see 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 opinion, not knowledge and certainty. This way of getting and improving our knowledge in substances only by experience and history, which is all that the weakness of our faculties in this state of mediocrity, which we are in in this world, can attain to, makes me suspect that natural philosophy is not capable of being made a science. We are able, I imagine, to reach very little general knowledge concerning the species of bodies, and their several properties. Experiments and historical observations we may have, from which we may draw advantages of ease and health, and thereby increase our stock of conveniences for this life; but beyond this, I fear our talents reach not, nor are our faculties, as I guess, able to advance. §11. We are fitted for moral knowledge and natural improvements. From whence it is obvious to conclude, that since our faculties are not fitted to penetrate into the internal fabric and real essences of bodies; but yet plainly discover to us the being of a God, and the knowledge of ourselves, enough to lead us into a full and clear discovery of our duty and great concernment; it will become us, as rational creatures, to employ those faculties we have, about what they are most adapted to, and follow the direction of nature, where it seems to point us out the way. For it is rational to conclude, that our proper employment lies in those inquiries, and in that sort of knowledge which is most suited to our natural capacities, and carries in it our greatest interest, i. e. the condition of our eternal estate. Hence I think I may conclude, that morality is the proper science and business of mankind in general (who are both concerned and fitted to search out their summum bonum), as several arts, conversant about several parts of nature, are the lot and private talent of particular men, for the common use of human life, and their own particular subsistence in this world. Of what consequence the discovery of one natural body and its properties may be to human life, the whole great continent of America is a convincing instance; whose ignorance in useful arts, and want of the greatest part of the conveniences of life, in a country that abounded with all sorts of natural plenty, I think may be attributed to their ignorance of what was to be found in a very ordinary despicable stone, I mean the mineral of iron. And whatever we think of our parts or improvements in this part of the world, where knowledge and plenty seem to vie with each other; yet to any one that will seriously reflect on it, I suppose it will appear past doubt, that were the use of iron lost amongst us, we should in a few ages be unavoidably reduced to the wants and ignorance of the ancient savage Americans, whose natural endowments and provisions come no way short of those of the most flourishing and polite nations; so that he who first made known the use of that contemptible mineral, may be truly styled the father of arts, and author of plenty. § 12. But must beware of hypotheses, and wrong principles.-I would not therefore be thought to disesteem or dissuade the study of nature. I readily agree, the contemplation of his works gives us occasion to admire, revere, and glorify their author: and if rightly directed, may be of greater benefit to mankind, than the monuments of exemplary charity that have, at so great charge, been raised by the founders of hospitals and alms-houses. He that first invented printing, discovered the use of the compass, or made public the virtue and right use of kinkina, did more for the propagation of knowledge, for the supply and increase of useful commodities, and saved more from the grave, than those who built colleges, work-houses, and hospitals. All that I would say, is, that we should not be too forwardly possessed with the opinion or expectation of knowledge, where it is not to be had, or by ways that will not attain to it that we should not take doubtful systems to complete sciences; nor unintelligible notions for scientifical demonstrations. In the knowledge of bodies, we must be content to glean what we can from particular experiments; since we cannot, from a discovery of their real essences, grasp at a time whole sheaves; and in bundles comprehend the nature and properties of whole species together. Where our inquiry is concerning co-existence, or repugnancy to co-exist, which by contemplation of our ideas we cannot discover; their experience, observation, and natural history, must give us by our senses, and by retail, an insight into corporeal substances. The knowledge of bodies we must get by our senses, warily employed in taking notice of their qualities and operations on one another; and what we hope to know of separate spirits in this world, we must, I think, expect only from revelation. He that shall consider how little general maxims, precarious principles, and hypotheses laid down at pleasure, have promoted true knowledge, or helped to satisfy the inquiries of rational men after real improvements; how little, I say, the setting out at that end has, for many ages together, advanced men's progress towards the knowledge of natural philosophy; will think we have reason to thank those, who in this latter age have taken another course, and have trod out to us, though not an easier way to learned ignorance, yet a surer way to profitable knowledge. § 13. The true use of hypotheses.-Not that we may not, to explain any phenomena of nature, make use of any probable hypothesis whatsoever. Hypotheses, if they are well made, are at least great helps to the memory, and often direct us to new discoveries. But my meaning is, that we should not take up any one too hastily (which the mind, that would always penetrate into the causes of things, and have primciples to rest on, is very apt to do), till we have very well examined particulars, and made several experiments in that thing which we would explain by our hypotheses, and see whether it will agree to them all; whether our principles will carry us quite through, and not be as inconsistent with one phenomenon of nature, as they seem to accommodate and explain another. And at least that we take care that the name of principles deceive us not, nor impose upon us, by making us receive that for an unquestionable truth, which is really, at best, but a very doubtful conjecture; such as are most (I had almost said all) of the hypotheses in natural philosophy. §14. Clear and distinct ideas with settled names, and the finding of those which shew their agreement or disagreement, are the ways to enlarge our knowledge. But whether natural philosophy be capable of certainty or no, the ways to enlarge our knowledge, as far as we are capable, seem to me, in short, to be these two : First, The first is to get and settle in our minds determined ideas of those things, whereof we have general or specific names; at least so many of them as we would consider and improve our knowledge in, or reason about. And if they be specific ideas of substances, we should endeavour also, to make them as complete as we can, whereby I mean, that we should put together as many simple ideas, as being constantly observed to co-exist, may perfectly determine the species; and each of those simple ideas, which are the ingredients of our complex ones, should be clear and distinct in our minds: for it being evident that our knowledge cannot exceed our ideas, as far as they are either imperfect, confused, or obscure, we cannot expect to have certain, perfect, or clear knowledge. Secondly, The other is the art of finding out those intermediate ideas, which may shew us the agreement or repugnancy of other ideas, which cannot be immediately compared. § 15. Mathematics an instance of it.-That these two (and not the relying on maxims, and drawing consequences from some general propositions) are the right methods of improving our knowledge in the ideas of other modes, besides those of quantity, the consideration of mathematical knowledge will easily inform us. Where first we shall find, that he that has not a perfect and clear idea of those angles or figures of which he desires to know any thing, is utterly thereby incapable of any knowledge about them. Suppose but a man not to have a perfect exact idea of a right angle, a scalenum, or trapezium; and there is nothing more certain, than that he will in vain seek any demonstration about them. Farther it is evident, that it was not the influence of those maxims which are taken for principles in mathematics, that hath led the masters of that science into those wonderful discoveries they have made. Let a man of good parts know all the maxims generally made use of in mathematics ever so perfectly, and contemplate their extent and consequences as much as he pleases, he will, by their assistance, I suppose, scarce ever come to know, that the square of the hypothenuse in a right-angled triangle, is equal to the squares of the two other sides. The knowledge that "the whole is equal to all its parts," and "if you take equals from equals, the remainder will be equal," &c. helped him not, I presume, to this demonstration: and a man may, I think, pore long enough on those axioms, without ever seeing one jot the more of mathematical truths. They have been discovered by the truths otherwise applied; the mind had other objects, other views before it, far different from those maxims, when it first got the knowledge of such kind of truths in mathematics, which men, well enough acquainted with those received axioms, but ignorant of their method who first made those demonstrations, can never sufficiently admire. And who knows what methods, to enlarge our knowledge in other parts of science, may hereafter be invented, answering that of algebra in mathematics, which so readily finds out the ideas of quantities to measure others by, whose equality or proportion we could otherwise very hardly, or perhaps never, come to know? CHAP. XIII. SOME FARTHER CONSIDERATIONS CONCERNING Our § 1. Our knowledge partly necessary, partly voluntary. knowledge, as in other things, so in this, has so great a conformity with our sight, that it is neither wholly necessary, nor wholly voluntary. If our knowledge were altogether necessary, all men's knowledge would not only be alike, but every man would know all that is knowable; and if it were wholly voluntary, some men so little regard or value it, that they would have extreme little, or none at all. Men that have senses, cannot choose but receive some ideas by them; and if they have memory, they cannot but retain some of them; and if they have any distinguishing faculty, cannot but perceive the agreement or disagreement of some of them one with another; as he that has eyes, if he will open them by day, cannot but see some objects, and perceive a difference in them. But though a man, with his eyes open in the light, cannot but see; yet there be certain objects, which he may choose whether he will turn his eyes to; there may be in his reach a book containing pictures and discourses capable to delight or instruct him, which yet he may never have the will to open, never take the pains to look into. § 2. The application voluntary; but we know as things are, not as we please.-There is also another thing in a man's power, and that is, though he turns his eyes sometimes towards an object, yet he may choose whether he will curiously survey it, and with an intent application endeavour to observe accurately all that is visible in it. But yet, what he does see, he cannot see otherwise than he does. It depends not on his will to see that black which appears yellow; nor to persuade himself, |