God is a 3rd-grade being, consisting of the 3rd-level goodness; the 2nd-level spirit as Father-Son-Holy Spirit; and 1st-level matter that’s materially simple and efficiently free. Goodness is beyond being; it is less a thing than Creator of things. Goodness is therefore purely an ad extra force whose own existence is inseparable from its self-expression in creatures.
The Father is an intellect that knows and contemplates itself, which includes all ideal abstracta which in part take the form of possible worlds and possible things.
The Holy Spirit is the ideal procession from the Father as a thought. It is timeless.
The Son is the real procession from the Father as the thing known and grasped by the thought. It is eternal, combining within itself infinite past, fully seized present, and endless future.
The Father combines in Himself both the ideal and real as all 4 time periods.
God wills good to all, creating and infusing being — He loves without there being any object the non-possession of which gives Him displeasure.
Goodness seeks nothing for itself other than to diffuse itself into creatures. While the 2nd-level God’s power is ad intra and directed toward finding and maintaining His own happiness within Himself, goodness grants God the ad extra power to create other things, things distinct from Himself (also real and ideal), whoever they may be.
Therefore, ascribing straightforward existence to God is problematic. The 2nd-level God exists in the ordinary sense as being united with essence — in fact, as something whose essence is existence. Goodness exists as a creative force. The personality of the Son — and therefore of the other persons, as per Jn 14:9 — was revealed to us in part in His Incarnation. 3rd-level goodness is utterly mysterious and impenetrable to us.
But language is useful only about 1st- and 2nd-level substances, rather than about things that transcend being, like goodness. Language falters when referring to God’s 3rd level. God is good and goodness itself, but its nature is far beyond our grasp.