John Calvin Commentary Jeremiah 6:17

"And I set watchmen over you, [saying], Hearken to the sound of the trumpet; but they said, We will not hearken." — Jeremiah 6:17 (ASV)

This is an explanation of the last verse, yet it is not simply that; for the Prophet, by a comparison, emphasizes the stubbornness of the people. They were not only deaf to the Prophet’s warnings but would not be awakened by the sound of the trumpet, nor even pay attention to it. The sound of the trumpet should have penetrated their minds more than anything else for two reasons: because it was louder than any human voice, and also, because we do not usually hear the trumpet sounding except when war is near or when there is the fear of war.

Thus we see why the Prophet, after announcing his message, mentions the sound of the trumpet. It is as if he had said that not only were the prophets despised while teaching the people, but also that the sound of the trumpet, announcing the approach of war, was not heeded by them. The stupidity of the people—and not only their stupidity but, as I have said, their perverseness also—was more fully demonstrated than if the Prophet had simply said that they had resolved not to listen.