— 648 —
Clear and distinct Ideas with settled Names, and the finding of those which shew their agreement, or disagreement, are the ways to enlarge our Knowledge.
      §14. But whether natural Philosophy be capable of Certainty, or
no, the ways to enlarge our Knowledge, as far as we are capable, seem
to me, in short, to be these two:
      First, The First is to get and settle in our Minds determined Ideas of
those Things, whereof we have general or specific Names; at least
of so many of them as we would consider and improve our Know-
ledge in, or reason about. And if they be specific Ideas of Substances,
we should endeavour also to make them as complete as we can,
whereby I mean, that we should put together as many simple
Ideas, as being constantly observed to co-exist, may perfectly
determine the Species: And each of those simple Ideas, which are the
ingredients of our Complex one, should be clear and distinct in our
Minds. For it being evident, that our Knowledge cannot exceed our
Ideas; as far as they are either imperfect, confused, or obscure, we
cannot expect to have certain, perfect, or clear Knowledge.
      Secondly, The other is the Art of finding out those Intermediate Ideas,
which may shew us the Agreement, or Repugnancy of other Ideas,
which cannot be immediately compared.
Locke Hum IV, 12, §14, p. 648