But I hope, before I have done, to make it evident, that this way of certainty, by the knowledge of our own ideas, goes a little further than bare imagination: and I believe it will appear that all the certainty of general truths a man has lies in nothing else.
3.

But what shall be the criterion of this agreement?
It is evident the mind knows not things immediately, but only by the intervention of the ideas it has of them.

Our knowledge, therefore, is real only so far as there is a CONFORMITY between our ideas and the reality of things.

But what shall be here the criterion?
How shall the mind, when it perceives nothing but its own ideas, know that they agree with things themselves?
This, though it seems not to want difficulty, yet, I think, there be two sorts of ideas that we may be assured agree with things.
4.

As, First All Simple Ideas are really conformed to Things.
FIRST, The first are simple ideas, which since the mind, as has been showed, can by no means make to itself, must necessarily be the product of things operating on the mind, in a natural way, and producing therein those perceptions which by the Wisdom and Will of our Maker they are ordained and adapted to.