in discourses and arguings about natural bodies and substantial things, to have learned, from the propriety of the language, the common but confused or very imperfect idea to which each word is applied, and to keep them to that idea in our use of them: but we must, by acquainting ourselves with the history of that sort of things, rectify and settle our complex idea belonging to each specific name; and in discourse with others (if we find them mistake us) we ought to tell what the complex idea is that we make such a name stand for. This is the more necessary to be done by all those who search after knowledge and philosophical verity, in that children, being taught words whilst they have but imperfect notions of things, apply them at random and without much thinking, and seldom frame determined ideas to be signified by them. Which custom (it being easy, and serving well enough for the ordinary affairs of life and conversation) they are apt to continue when they are men and so begin at the wrong end, learning words first and perfectly, but make the notions to which they apply those words afterwards very overtly. By this means it come to pass, that men speaking the proper language of their country, i. e. according to grammar-rules of that language, do yet speak very improperly of things themselves; and, by their arguing one with another, make but small progress in the discoveries of useful truths, and the knowledge of things, as they are to be found in themselves, and not in our imaginations; and it matters not much, for the improvement of our knowledge, how they are called.

25. Not easy to be made so. It were therefore to be wished that men, versed in physical inquiries, and acquainted with the several sorts of natural bodies, would set down those simple ideas wherein they observe the individuals of each sort constantly to agree. This would remedy a great deal of that confusion which comes from several persons applying the same name to a collection of a smaller or greater number of sensible qualities, proportionably as they have been more or less acquainted with or accurate in examining the qualities of any sort of things which come under one denomination. But a dictionary of this sort, containing, as it were, a natural history, requires too many hands, as well as too much time, cost, pains, and sagacity, ever to be hoped for; and till that be done, we must content ourselves with such definitions of the names of substances as explain the sense men use them in. And it would be well, where there is occasion, if they would afford us so much. This yet is not usually done; but men talk to one another, and dispute in words whose meaning is not agreed between them, out of a mistake that the significations of common words are certainly established, and the precise ideas they stand for perfectly known; and that it is a shame to be ignorant of them. Both which suppositions are false: no names of complex ideas having so settled, determined significations, that they are constantly used for the same precise ideas. Nor is it a shame for a man not to have a certain knowledge of any thing but by the necessary ways of attaining it; and so it is no discredit not to know what precise idea any sound stands for in another man's mind, without he declare it to

me by some other way than barely using that sound, there being no other way, without such a declaration, certainly to know it. Indeed, the necessity of communication by language brings men to an agreement in the signification of common words, within some tolerable latitude, that may serve for ordinary conversation: and so a man cannot be supposed wholly ignorant of the ideas which are annexed to words by common use, in a language familiar to him. But common use, being but a very uncertain rule, which reduces itself at last to the ideas of particular men, proves often but a very variable standard. But though such a dictionary as I have above mentioned will require too much time, cost, and pains to be hoped for in this age, yet, methinks, it is not unreasonable to propose, that words standing for things which are known and distinguished by their outward shapes, should be expressed by little draughts and prints made of them. A vocabulary made after this fashion would, perhaps, with more ease and in less time, teach the true signification of many terms, especially in languages of remote countries or ages, and settle truer ideas in men's minds of several things, whereof we read the names in ancient authors, than all the large and laborious comments of learned critics. Naturalists, that treat of plants and animals, have found the benefit of this way: and he that has had occasion to consult them, will have reason to confess that he has a clearer idea of apium or ibex from a little print of that herb or beast than he could have from a long definition of the names of either of them. And so no doubt he would have of strigil and sistrum, if, instead of "a curry-comb" and "cymbal," which are the English names dictionaries render them by, he could see stamped in the margin small pictures of these instruments, as they were in use amongst the ancients. Toga, tunica, pallium, are words easily translated by "gown," "coat," and "cloak:" but we have thereby no more true ideas of the fashion of those habits amongst the Romans, than we have of the faces of the tailors who made them. Such things as these, which the eye distinguishes by their shapes, would be best let into the mind by draughts made of them, and more determine the signification of such words than any other words set for them, or made use of to define them. But this only by the by.

26. Fifthly. By constancy in their signification.-Fifthly. If men will not be at the pains to declare the meaning of their words, and definitions of their terms are not to be had; yet this is the least can be expected, that, in all discourses wherein one man pretends to instruct or convince another, he should use the same word constantly in the same sense. If this were done, (which nobody can refuse without great disingenuity,) many of the books extant might be spared; many of the controversies in dispute would be at an end; several of those great volumes, swollen with ambiguous words now used in one sense and by and by in another, would shrink into a very narrow compass; and many of the philosophers' (to mention no other) as well as poets' works might be contained in a nut-shell.

27. When the variation is to be explained.-But, after all, the

provision of words is so scanty in respect of that infinite variety of thoughts, that men, wanting terms to suit their precise notion, will, notwithstanding their utmost caution, be forced often to use the same word in somewhat different senses. And though in the continuation of a discourse, or the pursuit of an argument, there be hardly room to digress into a particular definition, as often as a man varies the signification of any term; yet the import of the discourse will, for the most part, if there be no designed fallacy, sufficiently lead candid and intelligent readers into the true meaning of it: but where that is not sufficient to guide the reader, there it concerns the writer to explain his meaning, and show in what sense he there uses that term.

BOOK IV.

CHAPTER I.

OF KNOWLEDGE IN GENERAL.

1. Our knowledge conversant about our ideas.-Since the mind, in all its thoughts and reasonings, hath no other immediate object but its own ideas, which it alone does or can contemplate, it is evident that our knowledge is only conversant about them.

2. Knowledge is the perception of the agreement or disagreement of two ideas. Knowledge then seems to me to be nothing but the perception of the connexion and agreement, or disagreement and repugnancy, of any of our ideas. In this alone of our ideas. In this alone it consists. Where this perception is, there is knowledge; and where it is not, there, though we may fancy, guess, or believe, yet we always come short of knowledge. For, when we know that white is not black, what do we else but perceive that these two ideas do not agree? When we possess ourselves with the utmost security of the demonstration that the three angles of a triangle are equal to two right ones, what do we more but perceive, that equality to two right ones does necessarily agree to, and is inseparable from, the three angles of a triangle? *

3. This agreement fourfold.-But, to understand a little more distinctly wherein this agreement or disagreement consists, I think we may reduce it all to these four sorts: (1.) Identity, or diversity. (2.) Relation. (3.) Co-existence, or necessary connexion. (4.) Real existence.

4. First. Of identity or diversity.-First. As to the first sort of agreement or disagreement, viz. identity, or diversity. It is the first act of the mind, when it has any sentiments or ideas at all, to perceive its ideas, and, so far as it perceives them, to know each what it is, and thereby also to perceive their difference, and that one is not another. This is so absolutely necessary, that without it there could be no knowledge, no reasoning, no imagination, no distinct thoughts at all. By this the mind clearly and infallibly perceives each idea to agree with itself, and to be what it is; and all distinct *See Note at the end of this chapter, p. 386.-EDIT.

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ideas to disagree, i. e. the one not to be the other: and this it does without pains, labour, or deduction, but at first view, by its natural power of perception and distinction. And though men of art have reduced this into those general rules, "What is, is ;" and, "It is impossible for the same thing to be and not to be," for ready application in all cases wherein there may be occasion to reflect on it; yet it is certain that the first exercise of this faculty is about particular ideas. A man infallibly knows, as soon as ever he has them in his mind, that the ideas he calls "white" and round" are the very ideas they are, and that they are not other ideas which he calls "red" or "square." Nor can any maxim or proposition in the world make him know it clearer or surer than he did before, and without any such general rule. This, then, is the first agreement or disagreement which the mind perceives in its ideas, which it always perceives at first sight: and if there ever happen any doubt about it, it will always be found to be about the names, and not the ideas themselves, whose identity and diversity will always be perceived as soon and as clearly as the ideas themselves are, nor can it possibly be otherwise.

5. Secondly. Relative.-Secondly. The next sort of agreement or disagreement the mind perceives in any of its ideas may, I think, be called "relative," and is nothing but the perception of the relation between any two ideas, of what kind soever, whether substances, modes, or any other. For, since all distinct ideas must eternally be known not to be the same, and so be universally and constantly denied one of another, there could be no room for any positive knowledge at all, if we could not perceive any relation between our ideas, and find out the agreement or disagreement they have one with another, in several ways the mind takes of comparing them.

6. Thirdly. Of co-existence.-Thirdly. The third sort of agreement or disagreement to be found in our ideas, which the perception of the mind is employed about, is co-existence, or nonco-existence in the same subject; and this belongs particularly to substances. Thus when we pronounce concerning "gold" that it is fixed, our knowledge of this truth amounts to no more but this, that fixedness, or a power to remain in the fire unconsumed, is an idea that always accompanies and is joined with that particular sort of yellowness, weight, fusibility, malleableness, and solubility in aqua regia, which make our complex idea, signified by the word "gold."

7. Fourthly. Of real existence.-Fourthly. The fourth and last sort is that of actual real existence agreeing to any idea. Within these four sorts of agreement or disagreement is, I suppose, contained all the knowledge we have or are capable of: for, all the inquiries that we can make concerning any of our ideas, all that we know or can affirm concerning any of them, is, that it is or is not the same with some other; that it does or does not always co-exist with some other idea in the same subject; that it has this or that relation to some other idea; or that it has a real existence without the mind. Thus, "Blue is not yellow," is of identity. "Two tri

angles upon equal bases between two parallels are equal," is of relation. "Iron is susceptible of magnetical impressions," is of co-existence. "God is," is of real existence. Though identity and co-existence are truly nothing but relations, yet they are so peculiar ways of agreement or disagreement of our ideas, that they deserve well to be considered as distinct heads, and not under relation in general; since they are so different grounds of affirmation and negation, as will easily appear to any one who will but reflect on what is said in several places of this Essay. I should now proceed to examine the several degrees of our knowledge, but that it is necessary first to consider the different acceptations of the word "knowledge."

8. Knowledge actual or habitual.-There are several ways wherein the mind is possessed of truth, each of which is called "knowledge."

First. There is "actual knowledge," which is the present view the mind has of the agreement or disagreement of any of its ideas, or of the relation they have one to another.

Secondly. A man is said to know any proposition which having been once laid before his thoughts, he evidently perceived the agreement or disagreement of the ideas whereof it consists; and so lodged it in his memory, that, whenever that proposition comes again to be reflected on, he, without doubt or hesitation, embraces the right side, assents to and is certain of the truth of it. This, I think, one may call "habitual knowledge:" and thus a man may be said to know all those truths which are lodged in his memory by a foregoing clear and full perception, whereof the mind is assured past doubt as often as it has occasion to reflect on them. For, our finite understandings being able to think clearly and distinctly but on one thing at once, if men had no knowledge of any more than what they actually thought on, they would all be very ignorant; and he that knew most would know but one truth, that being all he was able to think on at one time.

9. Habitual knowledge twofold.-Of habitual knowledge there are also, vulgarly speaking, two degrees:

First. The one is of such truths laid up in the memory as, whenever they occur to the mind, it actually perceives the relation is between those ideas. And this is in all those truths whereof we have an intuitive knowledge, where the ideas themselves, by an immediate view, discover their agreement or disagreement one with another.

Secondly. The other is of such truths, whereof the mind having been convinced, it retains the memory of the conviction without the proofs. Thus a man that remembers certainly that he once perceived the demonstration that the three angles of a triangle are equal to two right ones, is certain that he knows it, because he cannot doubt of the truth of it. In his adherence to a truth where the demonstration by which it was at first known is forgot, though a man may be thought rather to believe his memory than really to know, and this way of entertaining a truth seemed formerly to me like something between opinion and knowledge, a