connexion between any secondary quality and any
modification whatsoever of any of the primary ones. And therefore there
are very few general propositions to be made concerning substances,
which can carry with them undoubted certainty.

8. Instance in Gold.

'All gold is fixed,' is a proposition whose truth we cannot be certain
of, how universally soever it be believed. For if, according to the
useless imagination of the Schools, any one supposes the term gold to
stand for a species of things set out by nature, by a real essence
belonging to it, it is evident he knows not what particular substances
are of that species; and so cannot with certainty affirm anything
universally of gold. But if he makes gold stand for a species determined
by its nominal essence, let the nominal essence, for example, be the
complex idea of a body of a certain yellow colour, malleable, fusible,
and heavier than any other known;--in this proper use of the word gold,
there is no difficulty to know what is or is not gold. But yet no other
quality can with certainty be universally affirmed or denied of gold,
but what hath a DISCOVERABLE connexion or inconsistency with that
nominal essence. Fixedness, for example, having no necessary connexion
that we can discover, with the colour, weight, or any other simple
idea of our complex one, or with the whole combination together; it is
impossible that we should certainly know the truth of this proposition,
that all gold is fixed.

9. No discoverable necessary connexion between nominal essence gold, and
other simple ideas.

As there is no discoverable connexion between fixedness and the colour,
weight, and other simple ideas of that nominal essence of gold; so,
if we make our complex idea of gold, a body yellow, fusable, ductile,
weighty, and fixed, we shall be at the same uncertainty concerning
solubility in AQUA REGIA, and for the same reason. Since we can never,
from consideration of the ideas themselves, with certainty affirm or
deny of a body whose complex idea is made up of yellow, very weighty,
ductile, fusible, and fixed, that it is soluble in AQUA REGIA: and so
on of the rest of its qualities. I would gladly meet with one general
affirmation concerning any will, no doubt, be presently objected, Is not
this an universal proposition, ALL GOLD IS MALLEABLE? To which I answer,
It is a very complex idea the word gold stands for. But then here is
nothing affirmed of gold, but that that sound st