— 588 —
Judgment may reach farther, but that is not Knowledge.
      §13. We are not therefore to wonder, if Certainty be to be found
in very few general Propositions made concerning Substances:
Our Knowledge of their Qualities and Properties go very seldom
farther than our Senses reach and inform us. Possibly inquisitive and
observing Men may, by strength of Judgment, penetrate farther,
and on Probabilities taken from wary Observation, and Hints well
laid together, often guess right at what Experience has not yet
discovered to them. But this is but guessing still; it amounts only
to Opinion, and has not that certainty, which is requisite to Know-
ledge. For all general Knowledge lies only in our own Thoughts, and
consists barely in the contemplation of our own abstract Ideas. Where-
ever we perceive any agreement or disagreement amongst them,
there we have general Knowledge; and by putting the Names of those
Ideas together accordingly in Propositions, can with certainty pro-
nounce general Truths. But because the abstract Ideas of Substances,
for which their specifick Names stand, whenever they have any
distinct and determinate signification, have a discoverable connexion
or inconsistency with but a very few other Ideas, the certainty of
universal Propositions concerning Substances, is very narrow and scanty
in that part, which is our principal enquiry concerning them; and
there is scarce any of the Names of Substances, let the Idea it is
applied to be what it will, of which we can generally, and with
certainty pronounce, that it has or has not this or that other
Quality belonging to it, and constantly co-existing or inconsistent
with that Idea, where-ever it is to be found.
Locke Hum IV, 6, §13, p. 588