But I go farther; and not content with asserting, that the conception of the existence of any object is no addition to the simple conception of it, I likewise maintain, that the belief of the existence joins no new ideas to those which compose the idea of the object.

When I think of God, when I think of him as existent, and when I believe him to be existent, my idea of him neither encreases nor diminishes.

But as it is certain there is a great difference betwixt the simple conception of the existence of an object, and the belief of it, and as this difference lies not in the parts or composition of the idea, which we conceive; it follows, that it must lie in the manner, in which we conceive it.
Suppose a person present with me, who advances propositions, to which I do not assent, that Caesar dyed in his bed, that silver is more fusible, than lead, or mercury heavier than gold; it is evident, that notwithstanding my incredulity, I clearly understand his meaning, and form all the same ideas, which he forms.

My imagination is endowed with the same powers as his; nor is it possible for him to conceive any idea, which I cannot conceive; nor conjoin any, which I cannot conjoin.

I therefore ask, Wherein consists the difference betwixt believing and disbelieving any proposition?
The answer is easy with regard to propositions, that are proved by intuition or demonstration.