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 'currycomb' and 'cymbal,' which are the English names [by which] dictionaries render them, he could see stamped in the margin small pictures of those 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. But this only by the by.

By constancy in their signification.-Fifthly,* If men will not be at the pains to declare the meaning of their Words, and [if] 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, many controversies would be at an end; several of those great volunes, 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.

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.

END OF THIRD BOOK.

BOOK IV.

CHAPTER I.

OF KNOWLEDGE IN GENERAL.

Our knowledge conversant about our ideas.-Since the mind, in all its thoughts and reasonings, has 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.

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 of our any 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 insepa parable from, the three angles of a triangle?

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 exist

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. 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

* This fourfold division comprises LOCKE's Predicables.'—ED.

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.

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 [which] the mind takes of comparing them.

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 Coexistence, 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.'