Through the gift of understanding, the Holy Spirit makes us plumb the depths of the mysteries of revelation. In a supernatural and therefore in a gratuitous way he teaches us the meaning of the deepest truths of faith. As St. Teresa says:
It is like one who, without having learned anything, or having taken the slightest trouble in order to learn to read, finds himself in possession of all existing knowledge; he has no idea how or whence it has come, since he has never done any work, even so much as was necessary for the learning of the alphabet.
“This last comparison, I think, furnishes some sort of explanation of this heavenly gift, for the soul suddenly finds itself learned, and the mystery of the Most Holy Trinity, together with other lofty things, is so clearly explained to it that there is no theologian with whom it would not have the boldness to contend in defense of the truth of these marvels.”
