Question about the Septuagint

A reader writes:Hi Mark! I was reading your book “By What Authority?” (Really great by the way) and was sharing some of it with my evangelical friend, and he brought up something I wasn’t sure how to answer. So I thought I’d ask you.In the book, you mention that the reason the Church canonized the seven extra books we have in the OT was because those books were part of the Septuagint, which would have been the bible the apostles used. Basically if it was good enough for the apostles it was good enough for the Church.But my friend asked, after I shared this with him, why we don’t accept all the Septuagint as Scripture then, with books like 3 Maccabees, as the Orthodox do? And I wasn’t sure what to say.Do you happen to know why the Church left out those other books of the Septuagint? Does this make Catholics to the Orthodox what Protestants are to us?I’m not a scholar of the Septuagint, but my *guess* would be that its content varied slightly in east and west.  If I’m right, I expect that Rome simply stuck with what the western Church did and the East stuck with the practice of the East.  Interestingly, the Council of Trent seems to have left the door open for the East to stick with their canon.  Its goal was to keep Protestants from removing books, not to prevent Eastern Churches from honoring the books they used that Catholics don’t.That’s just my guess though, based on how the ancient Churches typically handled such matters.  You’d need to talk to a Septuagint scholar to get the granular details.Basically, the way we got the Bible was that Christian communities said, “What are the books we read in our liturgies?  If we are reading them in