Derech Hashem – The Way of G-d 2:5:2
1.
Now, when it comes to G-d’s ability to perceive things, we know that He is all-knowing and that there’s nothing that He doesn’t know. For, He can see absolutely everything that’s happened in the past, what will happen in the future, and what is happening in the present, without exception 1.
2.
But we say that He perceives things 2 and that He judges or ordains things accordingly, though He limits this to the time-frame in which He wants to react to then 3. But we’ll expand upon that last point later on 4.
Footnotes:
1 That is, G-d sees and instantaneously understands what will happen in the future as a consequence of the past and the present — as well as what would have happened had things been otherwise. Aside from that, He also knows what He wants to happen in the ultimate future, and sees how to bring that about in light of the past and present provided Him.
Rambam says as much about G-d’s omniscience in Yesodei Hatorah 2:9, but Ramchal expands on that here and addresses G-d’s reactions to His knowledge.
2 Aside from knowing, which we’d just focused on. That’s to say that He also perceives the implications and consequences of what He knows.
3 See Avodah Zara 55a.
4 See 2:6:3 below.