An end, etc. The iteration of the word once more gives emphasis. The words read like an echo of Amos 8:2. The four corners (Hebrew, "wings") were probably, as with us, the north, east, south, and west.
The phrase had been used before in Isaiah 11:12, and the thought meets us again, in the form of the "four winds," in Daniel 11:4; Zechariah 2:6; Matthew 24:31; Mark 13:27. The "end" in this case is either that of the siege of Jerusalem, or that of the existence of Israel as a nation.
It was now drawing nigh—was, as we say, within measurable distance.