s deluded me all this
time. You asked me whether heat and cold, sweetness and
bitterness, were not particular sorts of pleasure and pain; to
which I answered simply that they were. Whereas I should have
thus distinguished:--those qualities as perceived by us, are
pleasures or pains; but not as existing in the external
objects. We must not therefore conclude absolutely, that there
is no heat in the fire, or sweetness in the sugar, but only
that heat or sweetness, as perceived by us, are not in the
fire or sugar."[276:8]

[Sidenote: The Application of the Epistemological Principle.]

Sect. 130. Here the argument touches upon profound issues. Philonous now
assumes the extreme empirical contention _that knowledge applies only to
its own psychological moment, that its object in no way extends beyond
that individual situation which we call the state of knowing_. The full
import of such an epistemology Berkeley never recognized, but he is
clearly employing it here, and the overthrow of Hylas is inevitable so
long as he does not challenge it or turn it against his opponent. This,
however, as a protagonist of Berkeley's own making, he fails to do, and
he plays into Philonous's hands by admitting that what is known only in
perception must for that reason _consist_ in perception. He frankly owns
"that it is vain to stand out any longer," that "colors, sounds, tastes,
in a word, all those termed _secondary qualities_, have certainly no
existence without the mind."[277:9]

Hylas has now arrived at the distinction between primary and secondary
qualities. "Extension, Figure, Solidity, Gravity, Motion, and Rest" are
the attributes of an external substance which is the cause of
sensations. But the same epistemological principle readily reduces these
also to dependence on mind, for, like the secondary qualities, their
content is given only in perception. Hylas is then driven to defend a
general material substratum, which is the cause of ideas, but to which
none of the definite content of these ideas can be attributed. In short,
he has put all the content of knowledge on the one side, and admitted
its inseparability from the perceiving spirit, and left the being of
things standing empty and forlorn on the other. This amounts, as
Philonous reminds him, to the denial of the reality of the known world.

"You are therefore, by your principles, forced to deny the
_reality_ of sensible