more or less comprehensive, with names annexed to them; in all which invariably, every more general term stands for such an idea as is but a part of any of those contained under it.-This may shew us the reason why in the defining of words, (which is nothing but declaring their signification) we make use of the genus, or next general word that comprehends it: this is not out of necessity, but sometimes to save the labour of enumerating the several simple ideas, and sometimes to conceal our ignorance. Though defining by the genus and differentia be the shortest way, yet it is not the only, and perhaps not the best way. A definition should enumerate those simple ideas that are combined in the signification of the term defined: and if instead of such enumeration we use the next general term, it is only for the sake of dispatch. I have no doubt but the definition of the term man," a solid extended substance, having life, sense, spontaneous motion, and the faculty of reason," would convey as clear an idea as the definition, "a rational animal." Languages are not always so logically made, as that every complex term can have its signification exactly expressed by others; or else those who made this rule have done ill to give us so few definitions conformable to it.

Generality and universality belong not to things, but are mere creatures of the Understanding, made for its use, and only concern signs, whether words or

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ideas. All things are particular in their existence, even those words and ideas which in their signification are general: for the signification they have is nothing but a relation added to them by the mind.-General words only signify sorts of things, being the signs of abstract ideas and the essences of the sorts of things are nothing but these abstract ideas.-Classing the sorts of things then is the workmanship of the understanding, which makes those abstract or general ideas. I mean not to deny that nature forms several things alike, (for nothing is more obvious, especially in the races of animals) but to class them under general names according to their similitude is the work of the mind. We shall never be able to keep, the species of things distinct, if we recur to supposed real essences, instead of determining them by our abstract ideas. No one will wonder that I consider these es sences or abstract ideas as artificial, who considers what different collections of simple ideas they denote in the minds of different men, even in the case of substances, where these ideas seem to be taken from the things themselves. But since the essences of things are thought by some, (and not without reason) to be wholly unknown, we will consider the several significations of the word essence. 1st, The proper original signification of the word (as is evident from the formation of it) is the being of any thing, whereby it is what it is: thus the internal constitution of

things, whereon their discoverable qualities depend, may be called their essence. 2dly, the most familiar use of the word essence is its application to the artificial constitution of genus and species; and then, it denotes that abstract idea with which any class of things agrees.

These two sorts of Essences may be termed real and nominal.

The name of any kind or sort of things always expresses the nominal essence.-Concerning the real essence of substances there are two opinions. Some use the word essence for they know not what; and suppose a certain number of essences, according to which all natural things are made, and of which each partakes, so as to be of this or that species. Others, more rationally, suppose all natural things to have a real but unknown constitution of their insensible parts, whence are derived those sensible qualities by which we distinguish them into sorts. The former of these notions has, I think, very much perplexed the knowledge of natural things. The frequent production of monsters in all the species of animals is a difficulty that cannot consist with this hypothesis; since it is as impossible that two things, partaking of the same real essence, should have different properties, as that the properties of two circles should be different. Besides, the supposition of unknown essences is so wholly useless, as to be a sufficient reason

for our rejecting it, and 'contenting ourselves with such essences as come within the reach of our knowledge; which, when seriously considered, will be found to be nothing else than those abstract complex ideas, to which we have annexed distinct general names. The real and nominal essence is the same in simple ideas and modes, but different in substances: thus, a figure including a space between three lines is the real as well as nominal essence of a triangle; it being not only the abstract idea to which the general name is annexed, but the very being of the thing itself, that foundation from which all its properties flow.Whereas the two essences of the ring on my finger are apparently different: for the real constitution of its inseparable parts, (on which depend the properties of colour, weight, fusibility, &c.) makes it Gold; which name is therefore its nominal essence.-We are told that essences are all ingenerable and incorruptible: now this cannot be true of the real constitutions of things, which begin and perish with the things themselves: for all things that exist, except their author, are liable to change. What is grass to day, is to-morrow the flesh of a sheep, and soon becomes part of a man, where it is evident that the real essence perishes with each change.

But essences considered as Ideas established in the mind with names annexed, are supposed to remain the same, whatever mutations the particular substances

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are liable to.-The ideas of man and horse reman the same whatever change the species may undergo; so that the essence of a species may remain safe and intire without the existence of one individual of the kind. Were there now no circle actually existing in the world, the idea annexed to the name would not cease to be what it is, and to shew what figure has a right to the name Circle. Though there had never been in nature such a beast as an Unicorn, yet supposing the name to denote a complex abstract idea that has no inconsistency in itself, the essence of an unicorn is as intelligible, and the idea as permanent as that of a man. trine of the immutability of essences proves them to be only abstract ideas; and is founded on the relation established between them and certain sounds as signs of them; which will always be true, as long as the same name can have the same signification.

Hence it is evident that the doc

CHAP. IV.

OF THE NAMES OF SIMPLE IDEAS.

ALL words signify immediately only the ideas in the mind of the speaker: but the names of simple ideas, mixed modes, (under which I comprise rela