John Calvin Commentary Jeremiah 50:36

"A sword is upon the boasters, and they shall become fools; a sword is upon her mighty men, and they shall be dismayed." — Jeremiah 50:36 (ASV)

He repeats the same thing, but in other words; and in the first clause, he mentions diviners whom he previously called wise men. He now calls them by their true and proper name, for בדים, bedim, means mendacious men as well as falsehoods. He now calls those impostors to whom he previously conceded the name of wise men.

But when he called them wise men, he spoke according to the common opinion and was unwilling to contend with the Chaldeans regarding the character of their wisdom. However, he at the same time made known the impositions of those who boasted that they had close communication with God and angels, while they pronounced by the stars what was to come.

That art itself would indeed be worthy of praise, if men preserved moderation. But since human curiosity is insatiable, they wandered here and there, overleaped all limits, and thus perverted the whole order of nature. The Chaldeans, then, were not genuine but, on the contrary, spurious astrologers.

This is the reason why the Prophet now calls them liars, for we have previously seen that it was a mere imposition when the Chaldeans held that the whole life of man is subject to the influence of the stars. Hence he exhorted the faithful to fear no dangers from the stars. It is no wonder, then, that the Prophet now charges all the diviners with falsehoods, who yet proudly arrogated to themselves the name of wise men. They shall be infatuated, he says. The verb יאל, ial, indeed means to begin, but in Niphal it means to become foolish, or to be infatuated.

Then he says, The sword shall be on her valiant men; whom he previously called chief men or princes, שרים, sherim, he now calls strong, גברים, geberim, or those who excelled in valor. The substance of it all is that whatever wisdom Babylon arrogated to itself would become folly, and the valor in which it prided itself would vanish.

For he says that they would be broken in pieces. The verb חתת, chetat, means to be broken; but as we have seen elsewhere, it is often applied to the mind, and then it means to dread or to be terrified. He then says that the valiant would not be able to stand when the sword was upon them, for they would become, as it were, lifeless; or, at least, they would become so weak as to think of nothing but flight.