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 that 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 notions, 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 can 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 shew in what sense he there uses that term.

BOOK IV.-CHAP. 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 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?*

The placing of certainty, as Mr. Locke does, in the perception of the agreement or disagreement of our ideas, the Bishop of Worcester suspects may be of dangerous conse

§ 3. This agreement fourfold.-But to understand a little more distinctly, wherein this agreement or disagreement consists, I think quence to that article of faith which he has endeavoured to defend: to which Mr. Locke answers: "Since your lordship hath not, as I remember, shewn, or gone about to shew, how this proposition, viz. that certainty consists in the perception of the agreement or disagreement of two ideas, is opposite or inconsistent with that article of faith which your lordship has endeavoured to defend; it is plain, it is but your lordship's fear, that it may be of dangerous consequence to it, which, as I humbly conceive, is no proof that it is any way inconsistent with that article.

"Nobody, I think, can blame your lordship, or any one else, for being concerned for any article of the Christian faith; but if that concern (as it may, and as we know it has done) makes any one apprehend danger, where no danger is, are we, therefore, to give up and condemn any proposition, because any one, though of the first rank and magnitude, fears it may be of dangerous consequence to any truth of religion, without shewing that it is so? If such fears be the measures whereby to judge of truth and falsehood, the affirming that there are antipodes, would be still a heresy; and the doctrine of the motion of the earth must be rejected, as overthrowing the truth of the scripture, for of that dangerous consequence it has been apprehended to be, by many learned and pious divines, out of their great concern for religion. And yet, notwithstanding those great apprehensions of what dangerous consequence it might be, it is now universally received by learned men, as an undoubted truth; and writ for by some, whose belief of the scripture is not at all questioned; and particularly, very lately, by a divine of the Church of England, with great strength of reason, in his wonderfully ingenious New Theory of the Earth.

"The reason your lordship gives of your fears, that it may be of such dangerous consequence to that article of faith, which your lordship endeavours to defend, though it occur in more places than one, is only this, viz. That it is made use of by ill men to do mischief, i. e. to oppose that article of faith, which your lordship hath endeavoured to defend. But, my lord, if it be a reason to lay by any thing as bad, because it is, or may be, used to an ill purpose, I know not what will be innocent enough to be kept. Arms, which were made for our defence, are sometimes made use of to do mischief; and yet they are not thought of dangerous consequence for all that. Nobody lays by his sword and pistols, or thinks them of such dangerous consequence as to be neglected, or thrown away, because robbers, and the worst of men, sometimes make use of them to take away honest men's lives or goods. And the reason is, because they were designed, and will serve, to preserve them. And who knows but this may be the present case? If your lordship thinks, that placing of certainty in the perception of the agreement or disagreement of ideas, be to be rejected as false, because you apprehend it may be of dangerous consequence to that article of faith: on the other side, perhaps others, with me, may think it a defence against error, and so (as being of good use) to be received and adhered to.

"I would not, my lord, be hereby thought to set up my own, or any one's, judgment against your lordship's. But I have said this only to shew, whilst the argument lies for or against the truth of any proposition, barely in an imagination that it may be of consequence to the supporting or overthrowing of any remote truth; it will be impossible, that way, to determine of the truth or falsehood of that preposition. For imagination will be set up against imagination, and the stronger probably will be against your lordship; the strongest imaginations being usually in the weakest heads. The only way, in this case, to put it past doubt, is to shew the inconsistency of the two propositions; and then it will be seen, that one overthrows the other; the true, the false one.

"Your lordship says, indeed, this is a new method of certainty. I will not say so myself, for fear of deserving a second reproof from your lordship, for being too forward to assume to myself the honour of being an original. But this, I think, gives me occasion, and will excuse me from being thought impertinent, if I ask your lordship whether there be any other, or older, method of certainty? and what it is? For if there be no other, nor older than this, either this was always the method of certainty, and so mine is no new one; or else the world is obliged to me for this new one, after having been so long in the want of so necessary a thing as a method of certainty. If there be an older, I am sure your lordship cannot but know it; your condemning mine as new, as well as your thorough insight into antiquity, cannot but satisfy every body that you do. And therefore to set the world right in a thing of that great concernment, and to overthrow mine, and thereby prevent the dangerous consequence there is in my having unreasonably started it, will not, I humbly conceive, misbecome your lordship's care of that article you have endeavoured to defend, nor the good-will you bear to truth in general. For I will be answerable for myself, that I shall; and I think I may be for all others, that they all will give off the placing of certainty

a In his second letter to the Bishop of Worcester.

we may reduce it all to these four sorts: 1. Identity or diversity. 2. Relation. S. Co-existence or necessary connexion. 4. Real existence.

in the perception of the agreement or disagreement of ideas, if your lordship will be pleased to shew that it lies in any thing else.

"But truly, not to ascribe to myself an invention of what has been as old as knowledge is in the world, I must own I am not guilty of what your lordship is pleased to call starting new methods of certainty. Knowledge, ever since there has been any in the world, has consisted in one particular action in the mind; and so, I conceive, will continue to do to the end of it. And to start new methods of knowledge, or certainty (for they are to me the same thing), i. e. to find out and propose new methods of attaining knowledge, either with more ease and quickness, or in things yet unknown, is what I think nobody could blame; but this is not that which your lordship here means, by new methods of certainty. Your lordship, I think, means by it, the placing of certainty in something, wherein either it does not consist, or else wherein it was not placed before now; if this be to be called a new method of certainty. As to the latter of these, I shall know whether I am guilty or no, when your lordship will do me the favour to tell me wherein it was placed before; which your lordship knows I professed myself ignorant of, when I writ my book, and so I am still. But if starting new methods of certainty, be the placing of certainty in something wherein it does not consist; whether I have done that or no, I must appeal to the expe

rience of mankind.

"There are several actions of men's minds, that they are conscious to themselves of performing, as willing, believing, knowing, &c. which they have so particular a sense of, that they can distinguish them one from another; or else they could not say, when they willed, when they believed, and when they knew any thing. But though these actions were different enough from one another, not to be confounded by those who spoke of them, yet nobody, that I have met with, had, in their writings, particularly set down wherein the act of knowing precisely consisted.

"To this reflection upon the actions of my own mind, the subject of my essay concerning Human Understanding naturally led me; wherein if I have done any thing new, it has been to describe to others, more particularly than had been done before, what it is their minds do when they perform that action which they call knowing; and if, upon examination, they observe I have given a true account of that action of their minds in all the parts of it, I suppose it will be in vain to dispute against what they find and feel in themselves. And if I have not told them right and exactly what they find and feel in themselves, when their minds perform the act of knowing, what I have said will be all in vain; men will not be persuaded against their senses. Knowledge is an internal perception of their minds; and if, when they reflect on it, they find that it is not what I have said it is, my groundless conceit will not be hearkened to, but be exploded by every body, and die of itself; and nobody need to be at any pains to drive it out of the world. So impossible is it to find out, or start new methods of certainty, or to have them received if any one places it in any thing, but in that wherein it really consists; much less can any one be in danger to be misled into error, by any such new, and to every one visibly, senseless project. Can it be supposed, that any one could start a new method of seeing, and persuade men thereby, that they do not see what they do see? Is it to be feared that any one can cast such a mist over their eyes, that they should not know when they see, and so be led out of their way by it?

"Knowledge, I find in myself, and I conceive in others, consists in the perception of the agreement or disagreement of the immediate objects of the mind in thinking, which I call ideas; but whether it does so in others or no, must be determined by their own experience, reflecting upon the action of their mind in knowing; for that I cannot alter, nor, I think, they themselves. But whether they will call those immediate objects of their minds in thinking, ideas or no, is perfectly in their own choice. If they dislike that name, they may call them notions or conceptions, or how they please; it matters not, if they use them so as to avoid obscurity and confusion. If they are constantly used in the same and a known sense, every one has the liberty to please himself in his terms; there lies neither truth, nor error, nor science, in that: though those that take them for things, and not for what they are, bare arbitrary signs of our ideas, make a great deal ado often about them; as if some greater matter lay in the use of this or that sound. All that I know, or can imagine, of difference about them, is that those words are always best, whose significations are best known in the sense they are used; and so are least apt to breed confusion.

My lord, your lordship hath been pleased to find fault with my use of the new term, ideas, without telling me a better name for the immediate objects of the mind in thinking. Your lordship also has been pleased to find fault with my definition of knowledge, without doing me the favour to give me a better. For it is only about my definition of knowledge, that all this stir concerning certainty is made. For, with me, to know, and to be certain, is the same thing; what I know, that I am certain of; and what I am certain of, that I know.

§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 know

What reaches to knowledge, I think may be called certainty; and what comes short of certainty, I think cannot be called knowledge; as your lordship could not but observe in the 18th section of chap. iv. of my 4th book, which you have quoted.

My definition of knowledge stands thus: Knowledge seems to me to be nothing but the perception of the connexion and agreement, or disagreement and repugnancy, of any of our ideas. This definition your lordship dislikes, and apprehends it may be of dangerous consequence as to that article of Christian faith which your lordship hath endeavoured to defend. For this there is a very easy remedy; it is but for your lordship to set aside this definition of knowledge by giving us a better, and this danger is over. But your lordship chooses rather to have a controversy with my book for having it in it, and to put me upon the defence of it; for which I must acknowledge myself obliged to your lordship for affording me so much of your time, and for allowing me the honour of conversing so much with one so far above me in all respects.

"Your lordship says, it may be of dangerous consequence to that article of Christian faith which you have endeavoured to defend. Though the laws of disputing allow bare denial as a sufficient answer to sayings, without any offer of a proof; yet, my lord, to shew how willing I am to give your lordship all satisfaction, in what you apprehend may be of dangerous consequence in my book, as to that article, I shall not stand still sullenly, and put your lordship upon the difficulty of shewing wherein that danger lies; but shall, on the other side, endeavour to shew your lordship that that definition of mine, whether true or false, right or wrong, can be of no dangerous consequence to that article of faith. The reason which I shall offer for it is this, because it can be of no consequence to it at all.

"That which your lordship is afraid it may be dangerous to, is an article of faith: that which your lordship labours and is concerned for, is the certainty of faith. Now, my lord, I humbly conceive the certainty of faith, if your lordship thinks fit to call it so, has nothing to do with the certainty of knowledge. As to talk of the certainty of faith, seems all one to me, as to talk of the knowledge of believing, a way of speaking not easy to me to understand. "Place knowledge in what you will; start what new methods of certainty you please, that are apt to leave men's minds more doubtful than before; place certainty on such grounds as will leave little or no knowledge in the world (for these are the arguments your lordship uses against my definition of knowledge): this shakes not at all, nor in the least concerns, the assurance of faith; that is quite distinct from it, neither stands nor falls with knowledge. "Faith stands by itself, and upon grounds of its own; nor can be removed from them, and placed on those of knowledge. Their grounds are so far from being the same, or having any thing common, that when it is brought to certainty, faith is destroyed; it is knowledge then, and faith no longer.

"With what assurance soever of believing I assent to any article of faith, so that I stedfastly venture my all upon it, it is still but believing. Bring it to certainty, and it ceases to be faith. I believe that Jesus Christ was crucified, dead, and buried, rose again the third day from the dead, and ascended into heaven:' let now such methods of knowledge or certainty be started, as leave men's minds more doubtful than before; let the grounds of knowledge be resolved into what any one pleases, it touches not my faith; the foundation of that stands as sure as before, and cannot be at all shaken by it; and one may as well say, that any thing that weakens the sight, or casts a mist before the eyes, endangers the hearing; as that any thing which alters the nature of knowledge (if that could be done) should be of dangerous consequence to an article of faith.

"Whether then I am, or am not mistaken, in the placing certainty in the perception of the agreement or disagreement of ideas; whether this account of knowledge be true or false, enlarges or straitens the bounds of it more than it should; faith stands still upon its own basis, which is not at all altered by it; and every article of that has just the same unmoved foundation, and the very same credibility, that it had before. So that, my lord, whatever I have said about certainty, and how much soever I may be out in it, if I am mistaken, your lordship has no reason to apprehend any danger to any article of faith from thence; every one of them stands upon the same bottom it did before, out of the reach of what belongs to knowledge and certainty. And thus much of my way of certainty by ideas; which, I hope, will satisfy your lordship how far it is from being dangerous to any article of the Christian faith whatsoever."

ledge, 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 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 happens 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 subtances, 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 non-co-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 and 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 triangles upon equal bases, between two parallels,