— 415 —
They are the Workmanship of the Understanding, but have their foundation in the similitude of things.       §13. I would not here be thought to forget, much less to deny,
that Nature in the Production of Things, makes several of them
alike: there is nothing more obvious, especially in the Races of
Animals, and all Things propagated by Seed. But yet, I think, we
may say, the sorting of them under Names, is the Workmanship of the
Understanding, taking occasion from the similitude it observes amongst
them, to make abstract general Ideas, and set them up in the mind,
with Names annexed to them, as Patterns, or Forms, (for in that
sence the word Form has a very proper signification,) to which, as
particular Things existing are found to agree, so they come to be of
that Species, have that Denomination, or are put into that Classis.
For when we say, this is a Man, that a Horse; this Justice, that
Cruelty; this a Watch, that a Jack; what do we else but rank Things
under different specifick Names, as agreeing to those abstract Ideas,
of which we have made those Names the signs? And what are the
Essences of those Species, set out and marked by Names, but those
abstract Ideas in the mind; which are, as it were, the bonds between
particular Things that exist and the Names they are to be ranked
under? And when general Names have any connexion with par-
ticular Beings, these abstract Ideas are the Medium that unites
them: so that the Essences of Species, as distinguished and
denominated by us, neither are, nor can be any thing but those
— 416 —
precise abstract Ideas we have in our minds. And therefore the
supposed real Essences of Substances, if different from our abstract
Ideas, cannot be the Essences of the Species we rank Things into.
For two Species may be one, as rationally, as two different Essences
be the Essence of one Species: And I demand, what are the altera-
tions may, or may not be made in a Horse, or Lead, without making
either of them to be of another Species? In determining the Species
of Things by our abstract Ideas, this is easy to resolve: but if any
one will regulate himself herein, by supposed real Essences, he will,
I suppose, be at a loss: and he will never be able to know when any
thing precisely ceases to be of the Species of a Horse, or Lead.
Locke Hum III, 3, §13, pp. 415-416