No existence of anything without us, but only of God, can certainly be known further than our senses inform us, (2) There is another sort of propositions, wherein is expressed the agreement or disagreement of OUR ABSTRACT IDEAS, and their dependence on one another.
Such propositions may be universal and certain.

So, having the idea of God and myself, of fear and obedience, I cannot but be sure that God is to be feared and obeyed by me: and this proposition will be certain, concerning man in general, if I have made an abstract idea of such a species, whereof I am one particular.

But yet this proposition, how certain soever, that 'men ought to fear and obey God' proves not to me the EXISTENCE of MEN in the world; but will be true of all such creatures, whenever they do exist: which certainty of such general propositions depends on the agreement or disagreement to be discovered in those abstract ideas.
14.

And all general Propositions that are know to be true concern abstract Ideas.
In the former case, our knowledge is the consequence of the existence of things, producing ideas in our minds by our senses: in the latter, knowledge is the consequence of the ideas (be they what they will) that are in our minds, producing there general certain propositions.

Many of these are called AETERNAE VERITATES, and all of them indeed are so; not from being written, all or any of them, in the minds of all men; or that they were any of them propositions in any one's mind, till he, having got the abstract ideas, joined or separated them by affirmation or negation.