His by virtue of His essence.

We therefore say: He must know His essence through itself. Once He knows His essence, since His essence is the cause of what follows from Him, He must know through His essence that it is the cause of what follows from Him. Thus, knowing His essence, He necessarily knows His effect.

His knowledge of His effect then necessarily entails His knowledge of all the other effects proceeding from Him, in both vertical and horizontal series. The vertical series is exemplified by the intellects, each of which is the cause of the intellect beneath it. The horizontal series occurs when two or more things proceed from a single cause, as when it is said that an intellect, a soul, and a celestial sphere emanate together from each intellect.”

He said:

“One might object: Why do you claim that His knowledge of His essence entails His knowledge of His effect? The explanation is this: either you say that His knowledge of His essence, considered as that particular essence, is the cause of His action involving His effect; or you say that His knowledge of His essence, considered as the cause of that effect, entails His existence through that effect. The first claim is disputed. Why, then, do you say that His knowledge of His particular essence—among whose concomitants and aspects is its being the cause of that effect—