John Calvin Commentary Jeremiah 50:35

"A sword is upon the Chaldeans, saith Jehovah, and upon the inhabitants of Babylon, and upon her princes, and upon her wise men." — Jeremiah 50:35 (ASV)

The Prophet proceeds with the same subject and employs the same manner of speaking. He denounces war on the Chaldeans as a celestial herald; and then, so that what he says might have more force and power, he presents the Persians and the Medes before us in the act of assailing and destroying Babylon.

Therefore, he now says in general, A sword on the Chaldeans; and secondly, he mentions the inhabitants of Babylon, for that city was the seat and head of the kingdom, as is well known. But since the power of that monarchy was considered unassailable by men, the Prophet adds that even though the chief men excelled in counsel, strength, and the art of war, yet a sword would be upon them. Finally, he adds that even though Babylon had its diviners, their knowledge would still be in vain.

He indeed uses an honorable name, yet he undoubtedly refers to astrologers, soothsayers, and other kinds of prophets. For we know that the whole nation was given to many superstitions, but they boasted of being the chief of all astrologers. Thus, soothsayers who practice their impostures are called Chaldeans, and this was formerly a common designation.

The Prophet means, then, that neither power, nor warlike skill, nor knowledge of any kind would be a defense for the Chaldeans, nor would the arts in which they gloried, even though they thought they were intimately acquainted with God; for by the stars they were accustomed to divine whatever was to come to pass.