ex idea
signified by some general name, comes into his mind; and it is in
reference to that that this or that quality is said to be essential.
So that if it be asked, whether it be essential to me or any other
particular corporeal being, to have reason? I say, no; no more than it
is essential to this white thing I write on to have words in it. But if
that particular being be to be counted of the sort MAN, and to have the
name MAN given it, then reason is essential to it; supposing reason
to be a part of the complex idea the name man stands for: as it is
essential to this thing I write on to contain words, if I will give it
the name TREATISE, and rank it under that species. So that essential and
not essential relate only to our abstract ideas, and the names annexed
to them; which amounts to no more than this, That whatever particular
thing has not in it those qualities which are contained in the abstract
idea which any general term stands for, cannot be ranked under that
species, nor be called by that name; since that abstract idea is the
very essence of that species.

5. The only essences perceived by us in individual substances are those
qualities which entitle them to receive their names.

Thus, if the idea of BODY with some people be bare extension or space,
then solidity is not essential to body: if others make the idea to which
they give the name BODY to be solidity and extension, then solidity is
essential to body. That therefore, and that alone, is considered as
essential, which makes a part of the complex idea the name of a sort
stands for; without which no particular thing can be reckoned of that
sort, nor be entitled to that name. Should there be found a parcel of
matter that had all the other qualities that are in iron, but wanted
obedience to the loadstone, and would neither be drawn by it nor receive
direction from it, would any one question whether it wanted anything
essential? It would be absurd to ask, Whether a thing really existing
wanted anything essential to it. Or could it be demanded, Whether this
made an essential or specific difference or no, since WE have no other
measure of essential or specific but our abstract ideas? And to talk of
specific differences in NATURE, without reference to general ideas in
names, is to talk unintelligibly. For I would ask any one, What is
sufficient to make an essential difference in nature between any two
particular beings, without any regard had to some abstra