18. Recapitulation.
Wherever we perceive the agreement or disagreement of any of our ideas, there is certain
knowledge: and wherever 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 shown
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.