of anything, which is the foundation of all those properties that are
combined in, and are constantly found to co-exist with the nominal
essence; that particular constitution which everything has within
itself, without any relation to anything without it. But essence, even
in this sense, RELATES TO A SORT, AND SUPPOSES A SPECIES. For, being
that real constitution on which the properties depend, it necessarily
supposes a sort of things, properties belonging only to species, and not
to individuals: v. g. supposing the nominal essence of gold to be a body
of such a peculiar colour and weight, with malleability and fusibility,
the real essence is that constitution of the parts of matter on which
these qualities and their union depend; and is also the foundation of
its solubility in aqua regia and other properties, accompanying that
complex idea. Here are essences and properties, but all upon supposition
of a sort or general abstract idea, which is considered as immutable;
but there is no individual parcel of matter to which any of these
qualities are so annexed as to be essential to it or inseparable from
it. That which is essential belongs to it as a condition whereby it
is of this or that sort: but take away the consideration of its being
ranked under the name of some abstract idea, and then there is nothing
necessary to it, nothing inseparable from it. Indeed, as to the real
essences of substances, we only suppose their being, without precisely
knowing what they are; but that which annexes them still to the species
is the nominal essence, of which they are the supposed foundation and
cause.


7. The nominal Essence bounds the Species to us.

The next thing to be considered is, by which of those essences it is
that substances are determined into sorts or species; and that, it is