St. Augustine Sayeth:
the New Testament lies hidden in the Old and the Old Testament is unveiled in the New.
(paraphrased quote from the Catechism)
Just for context, I looked this up and he actually said
Wherefore, in the Old Testament there is a veiling of the New, and in the New Testament there is a revealing of the Old.
We believe this in Catholicism and it's apparent from the way we structure the readings at Mass, the OT reading is always subtly explaining the Gospel one. But is that the case, is it just the Gospel (+Acts?) that is hidden in the OT. How do the epistles and revelation work in to the "hidden in / unveiled" equation?