Question About Baruch

A reader writes:A Protestant coworker is asking me questions about the seven “extra” books in the Catholic Bible. He recently asked me why in the book of Baruch it says that the Babylonian captivity would last seven generations when in Jeremiah it says it would last 70 years. I could not find an answer to this anywhere. Can you help? Thanks!The passage from Baruch to which you refer is said by the author (traditionally Jeremiah’s secretary) to be from a letter from Jeremiah to the exiles in Babylon.  It reads:Because of the sins which you have committed before God, you will be taken to Babylon as captives by Nebuchadnezzar, king of the Babylonians. Therefore when you have come to Babylon you will remain there for many years, for a long time, up to seven generations; after that I will bring you away from there in peace. (Bar 6:2–3).Jeremiah 29 is also a letter to the exiles in Babylon, with substantially the same message: You are there because of the sins of the nation.  God has not forgotten you and will bring you back, etc.  In the course of it, Jeremiah says:When seventy years are completed for Babylon, I will visit you, and I will fulfil to you my promise and bring you back to this place. (Je 29:10–11).There are various possibilities to account for the discrepancy.  Most biblical scholars would simply argue that Baruch is the work of a Hellenistic Jew writing several centuries after the historical Baruch to encourage Jews under Greek rule not to knuckle under to Greek paganism.  The “seven generations” would therefore be a play on the original Jeremiah’s promise, suggesting that just as their ancestors had escaped Babylonian domination, so they would escape Greek domination.It’s also possible the letter is by the original Jeremiah but