But adds no real Knowledge.
We can know then the truth of two sorts of propositions with perfect certainty.

The one is, of those trifling propositions which have a certainty in them, but it is only a verbal certainty, but not instructive.

And, secondly, we can know the truth, and so may be certain in propositions, which affirm something of another, which is a necessary consequence of its precise complex idea, but not contained in it: as that, the external angle of all triangles is bigger than either of the opposite internal angles.

Which relation of the outward angle to either of the opposite internal angles, making no part of the complex idea signified by the name triangle, this is a real truth, and conveys with it instructive real knowledge.
9.

General Propositions concerning Substances are often trifling.
We having little or no knowledge of what combinations there be of simple ideas existing together in substances, but by our senses, we cannot make any universal certain propositions concerning them, any further than our nominal essences lead us.