After considering what belongs to the angel's substance, we now proceed to his knowledge. This investigation will be fourfold. In the first place inquiry must be made into his power of knowledge: secondly, into his medium of knowledge: thirdly, into the objects known: and fourthly, into the manner whereby he knows them.

Under the first heading there are five points of inquiry:

(1) Is the angel's understanding his substance?

(2) Is his being his understanding?

(3) Is his substance his power of intelligence?

(4) Is there in the angels an active and a passive intellect?

(5) Is there in them any other power of knowledge besides the intellect?