It seems to me also that the fancy of Plato, that those stones which we call precious stones derive their lustre from a reflection, as it were, of the stones in that better land, is taken from the words of Isaiah in describing the city of God, “I will make your battlements of jasper, your stones shall be crystal, and your borders of precious stones;” and, “I will lay your foundations with sapphires.” Those who hold in greatest reverence the teaching of Plato, explain this myth of his as an allegory.
And the prophecies from which, as we conjecture, Plato has borrowed, will be explained by those who, leading a godly life like that of the prophets, devote all their time to the study of the sacred Scriptures, to those who are qualified to learn by purity of life, and their desire to advance in divine knowledge. For our part, our purpose has been simply to say that what we affirm of that sacred land has not been taken from Plato or any of the Greeks, but that they rather— living as they did not only after Moses, who was the oldest, but even after most of the prophets— borrowed from them, and in so doing either misunderstood their obscure intimations on such subjects, or else endeavoured, in their allusions to the better land, to imitate those portions of Scripture which had fallen into their hands.
Haggai expressly makes a distinction between the earth and the dry land, meaning by the latter the land in which we live. He says: “Yet once, and I will shake the heavens, and the earth, and the dry land, and the sea.”
Source: Against Celsus (New Advent)