Nature makes the Similitudes of Substances.
This, then, in short, is the case: Nature makes many PARTICULAR THINGS, which do agree one with another in many sensible qualities, and probably too in their internal frame and constitution: but it is not this real essence that distinguishes them into species; it is men who, taking occasion from the qualities they find united in them, and wherein they observe often several individuals to agree, range them into sorts, in order to their naming, for the convenience of comprehensive signs; under which individuals, according to their conformity to this or that abstract idea, come to be ranked as under ensigns: so that this is of the blue, that the red regiment; this is a man, that a drill: and in this, I think, consists the whole business of genus and species.
37.

The manner of sorting particular beings the work of fallible men, though nature makes things alike.
I do not deny but nature, in the constant production of particular beings, makes them not always new and various, but very much alike and of kin one to another: but I think it nevertheless true, that the boundaries of the species, whereby men sort them, are made by men; since the essences of the species, distinguished by different names, are, as has been proved, of man's making, and seldom adequate to the internal nature of the things they are taken from.

So that we may truly say, such a manner of sorting of things is the workmanship of men.
38.

Each abstract Idea, with a name to it, makes a nominal Essence.
One thing I doubt not but will seem very strange in this doctrine, which is, that from what has been said it will follow, that each abstract idea, with a name to it, makes a distinct species.

But who can help it, if truth will have it so?
For so it must remain till somebody can show us the species of things limited and distinguished by something else; and let us see that general terms signify not our abstract ideas, but something different from them.