— 538 —
Knowledge not always clear, where the Ideas are so.
      §15. But since our Knowledge is founded on, and employ’d
about our Ideas only, will it not follow from thence, that it is con-
formable to our Ideas; and that where our Ideas are clear and
distinct, or obscure and confused, our Knowledge will be so too?
To which I answer, No: For our Knowledge consisting in the per-
ception of the Agreement, or Disagreement of any two Ideas, its
clearness or obscurity, consists in the clearness or obscurity of that
Perception, and not in the clearness or obscurity of the Ideas them-
selves: v.g. a Man that has as clear Ideas of the Angles of a Triangle,
and of Equality to two right ones, as any Mathematician in the
World, may yet have but a very obscure Perception of their
Agreement, and so have but a very obscure Knowledge of it. But
Ideas, which by reason of their Obscurity or otherwise, are confused,
cannot produce any clear or distinct Knowledge; because as far as
any Ideas are confused, so far the Mind cannot perceive clearly,
whether they agree or disagree. Or to express the same thing in a
way less apt to be misunderstood. He that hath not determined the
Ideas to the Words he uses, cannot make Propositions of them,
Locke Hum IV, 2, §15, p. 538