John Calvin Commentary Jeremiah 51:2

"And I will send unto Babylon strangers, that shall winnow her; and they shall empty her land: for in the day of trouble they shall be against her round about." — Jeremiah 51:2 (ASV)

Here he explains himself more clearly, without the metaphor he had previously used. He no longer uses the likeness of wind when he declares that he would send fanners. At the same time, some take זארים (zarim) to mean aliens who would banish her; but this interpretation would be harsh. I then do not doubt that the Prophet alludes to the previously mentioned wind. He does not, indeed, continue that metaphor; but what he says still corresponds with it. Instead of wind, he now mentions fanners, or winnowers; but this can only be understood as referring to enemies. A clearer explanation is still found in the word empty, after he said that the Persians and the Medes would fan or winnow Babylon. He compares her, no doubt, to chaff. Just as chaff, when winnowed, falls to the ground, so he says a similar thing would happen to the Babylonians.

But he adds, And shall make empty her land—that is, the land of Babylon. He says that the whole country would be so plundered that nothing would be left. And he confirms this declaration: because they shall be, he says, around her. By this expression, he intimates that there would be no escape for the Chaldeans.

It often happens that people stealthily escape when pressed by their enemies; for though enemies may watch all passages, they often do not find all the hiding places. But the Prophet says that their enemies would so surround them that the Chaldeans would not be able to take anything with them that they might save from their enemies’ hands. He adds, in the day of evil. By this phrase, he again intimates that the Chaldeans were already devoted by God to destruction. It is, then, as if he had said that as soon as her enemies came, it would be all over with Babylon and the whole nation. How so? Because it would be the day of her utter ruin.