A very rough translation of Aquinas's article on whether we have through grace a higher knowledge of God than we do through natural reason. The Latin is here. The Dominican Fathers translation is here.
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We proceed to the thirteenth in this way.
[1] It seems that one does not have through grace a higher knowledge of God (altior cognitio Dei) than what one has through natural reason. For Dionysius says, in the book on Mystic Theology, that whoever is better united to God in this life, is united to him as to one wholly unknown, for he says this of Moses, who nonetheless obtained a sort of excellence in the knowledge by grace. But to be united to God while not knowing of Him what He is, this occurs also through natural reason. Therefore through grace God is not known to us more fully than He is through natural reason.
[2] Further, through natural reason we are not able to arrive at knowledge of divine things save through phantasms, and so it is according to knowledge by grace. For Dionysius says, Cael. Hier. chapter 1, that it is impossible the divine ray to enlighten us in any way, save as veiled about by a variety of sacred veils. Therefore by grace we do not know God more fully than by natural reason.
[3] Further, our understanding by the grace of faith adheres to God. But faith does not seem to be knowledge, for Gregory says, in Homil., that things that are not seen are had by faith, and not by apprehension (agnitionem). Therefore there is not added to us by grace some more excellent knowledge of God.
But on the contrary is what the apostle says, I Cor. 2, God has revealed to us through his Spirit that which none of the princes of this age knew, i.e., [none of] the philosophers, as the Gloss explains.
I reply that it must be said that by grace we have a more perfect knowledge of God than by natural reason. Which is clear in this way. The knowledge that we have by natural reason requires two things, namely, phantasms received from sensibles, and natural intelligible light, by whose power we abstract intelligible conceptions from them. And in both ways human knowledge is aided by revelation of grace. For both the natural light of the intellect is fortified by infusion of gracious light (per infusionem luminis gratuiti); and occasionally the phantasms in the human imagination are also divinely formed, so as better to express divine things than those that we received naturally from sensibles; as appears in prophetic visions. And occasionally also some sensible things are divinely formed, or even voices, in order to express something divine; as in the Baptism is seen the Holy Spirit in the form of a Dove, and the voice of the Father is heard, This is my beloved Son.
To the first it must therefore be said that, although by revelation of grace we do not know of God in this life what He is, and so we are conjoined to his as if to something unknown; still we known Him more fully, inasmuch as many and more excellent of His effects are demonstrated to us; and inasmuch as we attributed to Him some things from divine revelation, to which natural reason does not attain, as that God is three and one.
To the second it must be said that from phantasms, either received from the senses according to the natural order, or divinely formed in the imagination, we have so much the more excellent intellectual knowledge, the stronger the intelligible light in man is. And so by revelation we receive a fuller knowledge from phantasms, from infusion of the divine light.
To the third it must be said that faith is a sort of knowledge, inasmuch as the intellect is determined by faith to some knowable thing. But this determination to one does not proceed from the believer's vision, but from the vision of the one who is believed. And so, inasmuch as it lacks vision, it falls short of the rational cognition that is in knowledge [properly speaking] (scientia), for knowledge [properly speaking] (scientia) determines the intellect to one by vision and understanding of first principles.
