Let us suppose that there is in God, in so far as he is displayed through the human mind, an adequate idea, A.

The idea of this idea must also necessarily be in God, and be referred to him in the same way as the idea A (by II.

xx., whereof the proof is of universal application).

But the idea A is supposed to be referred to God, in so far as he is displayed through the human mind; therefore, the idea of the idea A must be referred to God in the same manner; that is (by II.

xi.
Coroll.), the adequate idea of the idea A will be in the mind, which has the adequate idea A; therefore he, who has an adequate idea or knows a thing truly (II.