51 Jerome then goes on to say that all interpretation rests on the literal sense, and that we are not to think that there is no literal sense merely because a thing is said metaphorically, for "the history itself is often presented in metaphorical dress and described figuratively." Indeed, he himself affords the best refutation of those who maintain that he says that certain passages have no historical meaning: "We are not rejecting the history, we are merely giving a spiritual interpretation of it.'' Once, however, he has firmly established the literal or historical meaning, Jerome goes on to seek our deeper and hidden meanings, as to nourish his mind with more delicate food. Thus he says of the Book of Proverbs - and he makes the same remark about other parts of the Bible - that we must not stop at the simple literal sense: "Just as we have to seek gold in the earth, for the kernel in the shell, for the chestnut's hidden fruit beneath its hairy coverings, so in Holy Scripture we have to dig deep for its divine meaning."
Source: Spiritus Paraclitus (Vatican.va)