“Explain to me a little further, sir,” I said. “What is it that you desire?” he asked. “Why, sir,” I said, “did these stones ascend out of the pit, and be applied to the building of the tower, after having borne these spirits?” “They were obliged,” he answered, “to ascend through water in order that they might be made alive; for, unless they laid aside the deadness of their life, they could not in any other way enter into the kingdom of God. Accordingly, those also who fell asleep received the seal of the Son of God.
For,” he continued, “before a man bears the name of the Son of God he is dead; but when he receives the seal he lays aside his deadness, and obtains life. The seal, then, is the water: they descend into the water dead, and they arise alive. And to them, accordingly, was this seal preached, and they made use of it that they might enter into the kingdom of God.” “Why, sir,” I asked, “did the forty stones also ascend with them out of the pit, having already received the seal?” “Because,” he said, “these apostles and teachers who preached the name of the Son of God, after falling asleep in the power and faith of the Son of God, preached it not only to those who were asleep, but themselves also gave them the seal of the preaching.
Accordingly they descended with them into the water, and again ascended. [But these descended alive and rose up again alive; whereas they who had previously fallen asleep descended dead, but rose up again alive.] By these, then, were they quickened and made to know the name of the Son of God. For this reason also did they ascend with them, and were fitted along with them into the building of the tower, and, untouched by the chisel, were built in along with them. For they slept in righteousness and in great purity, but only they had not this seal. You have accordingly the explanation of these also.”
Source: The Pastor (or "The Shepherd") (New Advent)