— 573 —
      §18. Where-ever we perceive the Agreement or Disagreement
of any of our Ideas there is certain Knowledge: and where-ever we
are sure those Ideas agree with the reality of Things, there is
certain real Knowledge. Of which Agreement of our Ideas with the
reality of Things, having here given the marks, I think I have
shewn wherein it is, that Certainty, real Certainty, consists. Which
whatever it was to others, was, I confess, to me heretofore, one of
those Desiderata which I found great want of.

Locke Hum IV, 4, §18, p. 573