In reply I said to her, “This is magnificent and marvellous. But who are the six young men who are engaged in building?” And she said, “These are the holy angels of God, who were first created, and to whom the Lord handed over His whole creation, that they might increase and build up and rule over the whole creation. By these will the building of the tower be finished.” “But who are the other persons who are engaged in carrying the stones?” “These also are holy angels of the Lord, but the former six are more excellent than these.
The building of the tower will be finished, and all will rejoice together around the tower, and they will glorify God, because the tower is finished.” I asked her, saying, “Lady, I should like to know what became of the stones, and what was meant by the various kinds of stones?” In reply she said to me, “Not because you are more deserving than all others that this revelation should be made to you— for there are others before you, and better than you, to whom these visions should have been revealed— but that the name of God may be glorified, has the revelation been made to you, and it will be made on account of the doubtful who ponder in their hearts whether these things will be or not.
Tell them that all these things are true, and that none of them is beyond the truth. All of them are firm and sure, and established on a strong foundation.”
Source: The Pastor (or "The Shepherd") (New Advent)