20.  Hence names independent of Real Essence.

By all which it is clear, that our distinguishing substances into species by names, is not at all founded on their real essences; nor can we pretend to range and determine them exactly into species, according to internal essential differences.

21.  But stand for such collections of simple ideas as we have made the Name stand for.

But since, as has been remarked, we have need of general words, though we know not the real essences of things; all we can do is, to collect such a number of simple ideas as, by examination, we find to be united together in things existing, and thereof to make one complex idea.  Which, though it be not the real essence of any substance that exists, is yet the specific essence to which our name belongs, and is convertible with it; by which we may at least try the truth of these nominal essences.  For example:  there be that say that the essence of body is extension; if it be so, we can never mistake in putting the essence of anything for the thing itself.  Let us then in discourse put extension for body, and when we would say that body moves, let us say that extension moves, and see how ill it will look.  He that should say that one extension by impulse moves another extension, would, by the bare expression, sufficiently show the absurdity of such a notion.  The essence of anything in respect of us, is the whole complex idea comprehended and marked by that name; and in substances, besides the several distinct simple ideas that make them up, the confused one of substance, or of an unknown support and cause of their union, is always a part:  and therefore the essence of body is not bare extension, but an extended solid thing; and so to say, an extended solid thing moves, or impels another, is all one, and as intelligible, as to say, body moves or impels.  Likewise, to say that a rational animal is capable of conversation, is all one as to say a man; but no one will say that rationality is capable of conversation, because it makes not the whole essence to which we give the name man.

22.  Our Abstract Ideas are to us the Measures of the Species we make in instance in that of Man.

There are creatures in the world that have shapes like ours, but are hairy, and want language and reason.  There are naturals amongst us that have perfectly our shape, but want reason, and some of them language too.  There are creatures, as it is said, (sit fides penes authorem, but there appears no contradiction that there should be such,) that, with language and reason and a shape in other things agreeing with ours, have hairy tails; others where the males have no beards, and others where the females have.  If it be asked whether these be all men or no, all of human species? it is plain, the question refers only to the nominal essence:  for those of them to whom the definition of the word man, or the complex idea signified by