— 482 —
Names of Substances referrd, First, To real Essences that cannot be known.
      §12. The Names of Substances have, as has been shewed, a double
reference in their ordinary use.
      First, Sometimes they are made to stand for, and so their signi-
fication is supposed to agree to, The real Constitution of Things, from
which all their Properties flow, and in which they all centre. But
this real Constitution, or (as it is apt to be called) Essence, being
utterly unknown to us, any Sound that is put to stand for it, must
be very uncertain in its application; and it will be impossible to
know, what Things are, or ought to be called an Horse, or Antimony,
when those Words are put for real Essences, that we have no Ideas
of at all. And therefore in this supposition, the Names of Substances
being referred to Standards that cannot be known, their signifi-
cations can never be adjusted and established by those Standards.
Locke Hum III, 9, §12, p. 482