— 582 —
The Truth of few universal Propositions concerning Substances, is to be known.
      §6. On the other side, the Names of Substances, when made use of
as they should be, for the Ideas Men have in their Minds, though
they carry a clear and determinate signification with them, will not
yet serve us to make many universal Propositions, of whose Truth we can be
certain. Not because in this use of them we are uncertain what Things
are signified by them, but because the complex Ideas they stand for,
are such Combinations of simple ones, as carry not with them any
discoverable connexion or repugnancy, but with a very few other
Ideas.
Locke Hum IV, 6, §6, p. 582