15 “For with righteousness shall He judge the world:” not a part of it, for He bought not a part: He will judge the whole, for it was the whole of which He paid the price. You have heard the Gospel, where it says, that when He comes, “He shall gather together His elect from the four winds.” He gathers all His elect from the four winds: therefore from the whole world. For Adam himself (this I had said before) signifies in Greek the whole world; for there are four letters, A, D, A, and M.
But as the Greeks speak, the four quarters of the world have these initial letters, 'Ανατολὴ, they call the East; Δύσις, the West; ῎Αρκτος, the North; Μεσημβρία, the South: you have the word Adam. Adam therefore has been scattered over the whole world. He was in one place, and fell, and as in a manner broken small, he filled the whole world: but the mercy of God gathered together the fragments from every side, and forged them by the fire of love, and made one what was broken.
That Artist knew how to do this; let no one despair: it is indeed a great thing, but reflect who that Artist was. He who made, restored: He who formed, reformed. What are righteousness and truth? He will gather together His elect with Him to the judgment, but the rest He will separate one from another; for He will place some on the right, others on the left hand. But what is more just, what more true, than that they shall not expect mercy from their Judge, who have refused to act mercifully, before their Judge come? But those who chose to act with mercy, with mercy shall be judged....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)