The son of a priest from the small town of Anathoth in Judah, the prophet Jeremiah dictated prophecies from the Lord to his secretary, Baruch. Because of Jeremiah’s lineage, he would have been raised a priest, though no record of his priestly service exists. Instead, God chose this man of undeniable courage to speak to the people of Judah on the Lord’s behalf—even though they would not listen.
Jeremiah was nearly twenty years old when he began to prophesy, and he continued in that office for the rest of his adult life, some forty years or more. Because his message held little weight with the people, Jeremiah’s prophecies reveal a substantial amount of emotional depth—often sorrow over the plight of God’s people or his own troubles (Jeremiah 12:1–4; 15:10).
https://insight.org/resources/bible/the-major-prophets/jeremiah