And therefore in this Psalm a healing doctrine is added, because either Idithun, or under his name the man himself, trained himself by spiritual exercise for the temptations to be undergone, that whoever is set in straits may subject himself to God and, if he has sinned before, may cease to sin and not be moved by a relapse into error. 'Once hath God spoken, these two things have I heard.' Once hath God spoken, and many things were heard, because he spoke not through letters and syllables. He spoke through riddles, he spoke through visions, he spoke through divisions of graces, he spoke through the spirit of individuals; but we speak many things and are scarcely heard. Once he spoke in the Law, and the same things he spoke again in the Gospel.
Or perhaps, as I think, because he spoke in many ways in the prophets, but last of all spoke in his Son, he spoke once — when he spoke in the Son — and there were heard even those things which had not been heard before by those to whom he had spoken through the prophets. Once therefore he spoke in the New Testament, and the Old Testament, which was not being heard, was heard, because the Lord himself said of the people of the Jews: 'They shall see and not see, they shall hear and not hear.' They shall hear with the bodily ear, but not hear with the hearing of the mind. To us therefore, that is, to the Church, he spoke once, and two things were heard, because in her we heard and understood those things which they who read had not understood, they who heard had not heard.
For Christ alone opened the human ear to know the mysteries; he alone loosed the seal of the book and unriddled the riddles of the prophets. And therefore he himself will render to each one according to his works; wherein he comprehends also the quality of the works, so that either he may restore the rewards of more numerous and better deeds to the individual merits, or, on the contrary, we may be weighed down both by the number and by the bitterness of our deserts.