But yet even this too disturbs not the certainty of that knowledge, which is still to be had by a due contemplation and comparing of those even nick-named ideas.
11.

Thirdly, Our complex Ideas of Substances have their Archetypes without us; and here knowledge comes short.
THIRDLY, There is another sort of complex ideas, which, being referred to archetypes without us, may differ from them, and so our knowledge about them may come short of being real.

Such are our ideas of substances, which, consisting of a collection of simple ideas, supposed taken from the works of nature, may yet vary from them; by having more or different ideas united in them than are to be found united in the things themselves.

From whence it comes to pass, that they may, and often do, fail of being exactly conformable to things themselves.
12.

So far as our complex ideas agree with those Archetypes without us, so far our Knowledge concerning Substances is real.
I say, then, that to have ideas of SUBSTANCES which, by being conformable to things, may afford us real knowledge, it is not enough, as in MODES, to put together such ideas as have no inconsistence, though they did never before so exist: v.g.the ideas of sacrilege or perjury, &c., were as real and true ideas before, as after the existence of any such fact.