That the Knowledge which Pure Spirits have of God through knowing their own Essence does not carry with it a Vision of the Essence of God

WE must further enquire whether this very knowledge, whereby separately subsistent intelligences and souls after death know God through knowing their own essences, suffices for their own happiness. For the investigation of this truth we must first show that the divine essence is not known by any such mode of knowledge. In no way can the essence of a cause be known in its effect, unless the effect be the adequate expression of the whole power of the cause.* But pure spirits know God through their own substances, as a cause is known through its effect inasmuch as each sees God as mirrored in another, and each sees God as expressed in himself.* But none of these pure spirits is an effect adequate to the power of God (B. II, Chapp. XXVI, XXVII). It is impossible therefore for them to see the divine essence by this method of knowledge.

2. An intelligible likeness, whereby a thing is understood in its substance must be of the same species as that thing, or rather it must be its species, -- thus the form of a house in the architect's mind is the same species as the form of the house which is in matter, or rather it is its species, -- for by the species of man you do not understand the essence of ass or horse.* But the nature of an angel is not the same as the divine nature in species, nay not even in genus (B. I, Chap. XXV).

3. Everything created is bounded within the limits of some genus or species. But the divine essence is infinite, comprising within itself every perfection of entire being (B. I, Chapp. XXVIII, XLIII). It is impossible therefore for the divine substance to be seen through any created medium.

Nevertheless a pure spirit by knowing its own substance knows the existence of God, and that God is the cause of all, and eminent above all, and removed (remotus) from all, not only from all things that are, but from all that the created mind can conceive. To this knowledge of God we also may attain in some sort: for from the effects of His creation we know of God that He is, and that He is the cause (sustaining principle) of other beings, super-eminent above other beings, and removed from all. And this is the highest perfection of our knowledge in this life: hence Dionysius says (De mystica theologia c. 2) that "we are united with God as with the unknown"; which comes about in this way, that we know of God what He is not, but what He is remains absolutely unknown. And to show the ignorance of this most sublime knowledge it is said of Moses that he drew nigh to the darkness in which God was (Exod. xx, 21).*

But because an inferior nature at its height attains only to the lowest grade of the nature superior to it, this knowledge must be more excellent in pure spirits than in us. For (a) the nearer and more express the effect, the more evidently apparent the existence of the cause. But pure spirits, that know God through themselves, are nearer and more express likenesses of God than the effects through which we know God.

(c) High dignity better appears, when we know to what other high dignities it stands preferred. Thus a clown, knowing the king to be the chief man in the kingdom, but for the rest knowing only some of the lowest officials of the kingdom, with whom he has to do, does not know the king's pre-eminence so well as another, who knows the dignity of all the princes of the realm. But we men know only some of the lowest of things that are. Though then we know that God is high above all beings, still we do not know the height of the Divine Majesty as the angels know it, who know the highest order of beings and God's elevation above them all.

3.48 : That the Final Happiness of Man is not in this Life
3.50 : That the Desire of Pure Intelligences does not rest satisfied in the Natural Knowledge which they have of God