Book III. them to make abstract general ideas, and fet them up in the mind, with names annexed to them, as patterns or forms (for in that fenfe the word form has a very proper fignification), to which as particular things exifting are found to agree, fo they come to be of that fpecies, have that denomination, or are put into that claffis. For when we say, this is a man, that a horfe; this juftice, that cruelty; this a watch, that a jack; what do we elfe but rank things under different specific names, as agreeing to thofe abftract ideas, of which we have made thofe names the figns? and what are the effences of thofe fpecies fet out and marked by names, but thofe abstract ideas in the mind, which are as it were the bonds between particular things that exift, and the names they are to be ranked under? And when general names have any connection with particular beings, thefe abftract ideas are the medium that unites them; so that the effences of fpecies, as diftinguifhed and denominated by us, neither are nor can be any thing but those precife abstract ideas we have in our minds; and therefore the fuppofed real effences of fubftances, if different from our abstract ideas, cannot be the effences of the fpecies we rank things into; for two fpecies may be one as rationally, as two different effences be the eflence of one fpecies and I demand what are the alterations may or may not be in a horfe or lead, without making either of them to be of another fpecies? In determining the fpecies of things by our abstract ideas, this is eafy to refolve but if any one will regulate himself herein by fuppofed real effences, he will, I suppose, be at a loss; and he will never be able to know when any thing precifely ceases to be of the fpecies of a horfe or lead. $14. Each diftinct abftract Idea is a diftinct Effence. NOR will any one wonder, that I fay thefe effences, or abftract ideas (which are measures of name, and the boundaries of fpecies), are the workmanship of the underftanding, who confiders, that at leaft the complex ones are often, in feveral men, different collections of fimple ideas; and therefore that is covetousness to one man, which is not fo to another. Nay, even in fubftances, where their abstract ideas feem to be taken from the things themselves, they are not conftantly the fame, no, not in that fpecies which is most familiar to us, and with which we have the most intimate acquaintance it having been more than once doubted, whether the fætus born of a woman were a man, even fo far as that it hath been debated, whether it were or were not to be nourished and baptized; which could not be, if the abstract idea of effence, to which the name man belonged, were of nature's making, and were not the uncertain and various collection of fimple ideas which the understanding puts together, and then abftracting it, af fixed a name to it; fo that in truth every diftinct abftra& idea is a diftinct effence, and the names that ftand for fuch distinct idens, are the names of things effentially different. Thus, a circle is as effentially different from an oval as a sheep from a goat, and rain is as effentially different from fnow as water from earth; that abstract idea which is the effence of one being impoffible to be communicated to the other. And thus any two abftract ideas, that in any part vary one from another, with two distinct names annexed to them, conftitute two dif tinct forts, or, if you pleafe, fpecies, as effentially dif ferent as any two the most remote or oppofite in the world. 15. Real and Nominal Effence. BUT ɓince the effences of things are thought by fome (and not without reafon) to be wholly unknown, it may not be amifs to confider the feveral fignifications of the word effence. First, Effence may be taken for the being of any thing, whereby it is what it is; and thus the real internal, but generally in fubftances unknown, conftitution of things, whereon their difcoverable qualities depend, may be called their effence. This is the proper original fignification of the word, as is evident from the formation of it; effentia, in its primary notation, fignifying properly being And in this fenfe it is ftill ufed, when we fpeak of the effence of particular things, without giving them any name. VOL. II. G Book III. Secondly, The learning and difputes of the fchools having been much bufied about genus and fpecies, the word effence has almoft loft its primary fignification; and instead of the real conftitution of things, has been almost wholly applied to the artificial conftitution of genus and Species. It is true, there is ordinarily fupposed a real constitution of the forts of things, and it is paft doubt there must be some real conftitution on which any collection of fimple ideas co-exifting muft depend. But it being evident, that things are ranked under names into forts or fpecies, only as they agree to certain abstract ideas, to which we have annexed thofe names, the effence of each genus or fort comes to be nothing but that abstract idea, which the general or fortal (if I may have leave fo to call it from fort, as I do general from genus) name ftands for; and this we fhall find to be that which the word effence imports in its moft familiar ufe. These two forts of effences, I fuppofe, may not unfitly be termed, the one the real, the other the nomi nal effence. 16. Conflant Connection between the name and nomi nal Effence. BETWEEN the nominal effence and the name, there is fo near a connection, that the name of any fort of things cannot be attributed to any particular being but what has this effence, whereby it anfwers that abstract idea, whereof that name is the fign. 17. Suppofition that Species are diffinguished by their real Effences, ufeless. CONCERNING the real effences of corporeal fubftances (to mention those only), there are, if I mistake not, two opinions. The one is of those, who, ufing the word ef fence for they know not what, fuppofe a certain number of thofe effences, according to which all natural things are made, and wherein they do exactly every one of them partake, and fo become of this or that species. The other and more rational opinion, is of thofe who look on all natural things to have a real but unknown conftitution of their infenfible parts, from which flow thofe fenfible qualities which ferve us to diftinguish them one from another, according as we have occafion to rank them into forts under common denominations. The former of these opinions, which fuppofes these effences as a certain number of forms or moulds, wherein all natural things that exift are caft, and do equally partake, has, I imagine, very much perplexed the knowledge of natural things. The frequent productions of monsters, in all the fpecies of animals, and of changelings, and other strange iffues of human birth, carry with them difficulties not poffible to confift with this hypothefts; fince it is as impoffible that two things, partaking exactly of the fame real effence, fhould have different properties, as that the two figures partaking in the fame real effence of a circle should have different properties. But were there no other reason againft it, yet the fuppofition of ef fences that cannot be known, and the making them nevertheless to be that which diftinguishes the fpecies of things, is so wholly useless and unferviceable to any part of our knowledge, that that alone were fufficient to make us lay it by, and content ourfelves with fuch effences of the forts or fpecies of things as come within the reach of our knowledge, which, when feriously confidered, will be found, as I have faid, to be nothing else but those abstract complex ideas, to which we have annexed diftinct general names. § 18. Real and nominal Effence the fame in fimple Ideas and Modes, different in Subftances. ESSENCES being thus diftinguished into nominal and real, we may farther obferve, that in the fpecies of fimple ideas and modes they are always the fame, but in fubftances always quite different. Thus, a figure including a space between three lines, is the real as well as nominal effence of a triangle, it being not only the abstract idea to which the general name is annexed, but the very effentia or being of the thing itself, that foundation from which all its properties flow, and to which they are all infeparably annexed. But it is far otherwife concerning that parcel of matter which makes the ring on my finger, wherein thefe two effences are apparently different; for it is the real conftitution of its infenfible parts on which G 2 depend all thofe properties of colour, weight, fufibility, fixednefs, &c. which makes it to be gold, or gives it a right to that name, which is therefore its nominal effence; fince nothing can be called gold but what has a confor mity of qualities to that abitract complex idea to which that name is annexed. But this diftinction of effences, belonging particularly to fubftances, we fhall, when we come to confider their names, have an occafion to treat of more fully. $ 19. Effences ingenerable and incorruptible. THAT fuch abfract ideas, with names to them, as we have been fpeaking of, are effences, may farther appear by what we are told concerning effences, viz. that they are all ingenerable and incorruptible; which cannot be true of the real conftitutions of things which begin and perish with them. All things that exift, befides their author, are all liable to change; efpecially thofe things we are acquainted with, and have ranked into bands under diftinct names or enfigns. Thus that which was grafs to-day, is to-morrow the flesh of a fheep, and within few days after becomes part of a man: In all which, and the like changes, it is evident their real effence, i. e. that conftitution whereon the properties of thefe feveral things depended, is deftroyed, and perishes with them. But effences being taken for ideas eftablished in the mind, with names annexed to them, they are fuppofed to remain steadily the fame, whatever mutations the particular fubftances are liable to; for whatever becomes of Alexander and Bucephalus, the ideas to which man and horfe are annexed, are fuppofed neverthelefs to remain in the fame; and fo the fences of those fpecies are preferved whole and undeftroyed, whatever changes happen to any, or all of the individuals of those Species. By this means, the effence of a species refts safe and entire, without the existence of fo much as one individual of that kind: For were there now no circle exifting any where in the world (as perhaps that figure exifts not any where exactly marked out), yet the idea annexed to that name would not ceafe to be what it is, nor cease to be as a pattern to determine which of |