7 “For I shall see Your heavens, the works of Your fingers”. We read that the law was written with the finger of God, and given through Moses, His holy servant: by which finger of God many understand the Holy Ghost. Wherefore if, by the fingers of God, we are right in understanding these same ministers filled with the Holy Ghost, by reason of this same Spirit which works in them, since by them all holy Scripture has been completed for us; we understand consistently with this, that, in this place, the books of both Testaments are called “the heavens.” Now it is said too of Moses himself, by the magicians of king Pharaoh, when they were conquered by him, “This is the finger of God.” And what is written, “The heavens shall be rolled up as a book.” Although it be said of this æthereal heaven, yet naturally, according to the same image, the heavens of books are named by allegory. “For I shall see,” he says, “the heavens, the works of Your fingers:” that is, I shall discern and understand the Scriptures, which You, by the operation of the Holy Ghost, hast written by Your ministers.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)