as well as nominal essence; and there is no secret reference of that
name to any other essence but that. But in SUBSTANCES, it is not so. For
though in that called GOLD, one puts into his complex idea what another
leaves out, and vice versa: yet men do not usually think that therefore
the species is changed: because they secretly in their minds refer that
name, and suppose it annexed to a real immutable essence of a thing
existing, on which those properties depend. He that adds to his complex
idea of gold that of fixedness and solubility in AQUA REGIA, which he
put not in it before, is not thought to have changed the species; but
only to have a more perfect idea, by adding another simple idea, which
is always in fact joined with those other, of which his former complex
idea consisted. But this reference of the name to a thing, whereof we
have not the idea, is so far from helping at all, that it only serves
the more to involve us in difficulties. For by this tacit reference to
the real essence of that species of bodies, the word GOLD (which, by
standing for a more or less perfect collection of simple ideas, serves
to design that sort of body well enough in civil discourse) comes to
have no signification at all, being put for somewhat whereof we have no
idea at all, and so can signify nothing at all, when the body itself is
away. For however it may be thought all one, yet, if well considered, it
will be found a quite different thing, to argue about gold in name, and
about a parcel in the body itself, v.g. a piece of leaf-gold laid before
us; though in discourse we are fain to substitute the name for the
thing.


20. The Cause of this Abuse, a supposition of Nature's working always
regularly, in setting boundaries to Species.

That which I think very much disposes men to substitute their names for