John Calvin Commentary Isaiah 21:10

"O thou my threshing, and the grain of my floor! that which I have heard from Jehovah of hosts, the God of Israel, have I declared unto you." — Isaiah 21:10 (ASV)

My thrashing, and the son of my floor. The wealth of that powerful monarchy, having dazzled the eyes of all people by its splendor, meant that what Isaiah foretold about its destruction might be considered unbelievable. Therefore, he directs their minds to God, to inform them that it was God who had undertaken to destroy Babylon, and that it is not by the will of humans, but by divine power, that such loftiness will fall to the ground. The “thrashing” and “the son of the floor” mean the same thing, for this type of expression is frequently used by Hebrew writers, who often repeat the same statement using different words.

This passage should be carefully observed, so that we may correct a vice that is natural to us: that of measuring the power of God by our own standard. Our weakness not only places us far below the wisdom of God, but we are also wicked and depraved judges of His works, and cannot be persuaded to view them in any other way than by what comes within the reach of human ability and wisdom. But we should always remember His almighty power, especially when our own reason and judgment fail us.

Thus, when the Church is so oppressed by tyrants that there seems to be no hope of deliverance, let us understand that the Lord will bring them low. By trampling on their pride and humbling their strength, He will show that they are His “threshing-floor,” for the subject of this prediction was not a person of low rank, but the most powerful and flourishing of all monarchies. The more they have exalted themselves, the more quickly they will be destroyed, and the Lord will execute His “threshing” upon them. Let us learn that what the Lord has presented here as a display of inconceivable ruin applies to people of the same kind.

That which I have heard from the Lord of hosts. When he says that he has “heard it from the Lord of hosts,” he sets a seal, as it were, on his prophecy, for he declares that he has not brought forward his own conjectures, but has received it from the Lord Himself. Here it is worthy of our notice that the servants of God should be strengthened by this boldness to speak in the name of God, as Peter also exhorts, He that speaketh, let him speak as the oracles of God (1 Peter 4:11). Impostors also boast of the name of God, but His faithful servants have the testimony of their conscience that they bring forward nothing but what God has commanded. Observe, also, that this confirmation was highly necessary, for the whole world trembled at the resources of this powerful monarchy.

From the Lord of hosts, the God of Israel. It is not without reason that he gives God these two titles. As for the former, it is indeed a title that always applies to God; but here, undoubtedly, the Prophet had in view the matter at hand, to contrast the power of God with all the troops of the Babylonians, for God has not just a single army, but innumerable armies, to subdue His enemies.

Again, he calls Him “the God of Israel,” because by destroying Babylon He showed Himself to be the defender and guardian of His people, for the overthrow of that monarchy secured freedom for the Jews. In short, all these things were done for the sake of the Church, which the Prophet has in view here; for it is not the Babylonians (who undoubtedly laughed at these predictions) whom he addresses, but believers, whom he exhorts to rest assured that, even though they were oppressed by the Babylonians, and scattered and tossed about, God would still take care of them.