So when Benedict XVI said that the LXX is "an independent textual witness", he was saying that, in any attempt to reconstruct an 'original text' of the Old Testament, the LXX is just as respectable piece of evidence as the MT (the Hebrew texts used in modern synagogues). The Reformation view that the 'Scriptures' should be translated from the 'authentic Hebrew Original' is a gross oversimplification. That's Common Sense, if you think about it: why should Hebrew manuscripts which date from hundreds of years AD be prioritised above the now lost Hebrew manuscripts which the Jewish translators in Alexandria two or three centuries BC had in front of them on their desks? Why should the LXX, 'the Bible' which S Paul knew and used, be viewed as inferior to the much later MT? Indeed: let me digress from the main thrust of my argument to say that it may well also have been Christ's Bible: the assumption that the Lord Himself always spoke Aramaic (or Hebrew) is dubious in view of the fact that he lived very near a large Greek city in a bilingual Palestine. (And did you know that the notices in the Temple at Jerusalem were in Greek?) S Mark records, in his Greek Gospel, that Christ spoke in Aramaic to the girl he raised to life and to the dumb man whom he cured. The most obvious conclusion to draw from that is that he normally spoke Greek but reverted to the local language, Aramaic, when raising a young girl or curing a handicapped man. In bilingual societies, it is common for the cosmopolitan international language of the world of men and of great affairs (English; Greek; French) to occupy a different sociological niche from that occupied by the old local language of hearth and family (Welsh; Aramaic; S Bernadette's Gascon). It was as a toddler that the Incarnate Word would have heard from his Mother the Aramaic term for Daddy, Abba. It was the language of mothers and children.
The LXX, then, is not a bit like old uncle Bob, of whom in polite company we are rather ashamed because of his uncouth manners ("It's the way he burps and dribbles as he eats his rice pudding with his mouth open ..."). And Alexandria (with which the LXX is associated) symbolises the height of Greek culture and civilisation. Athens had in comparison become something of a backwater. Alexandria was wealthy and sophisticated and it sucked into itself the artistic and literary resources of the Greek world. Its library, founded and sustained by royal patronage, was the greatest in the world. Its Librarians were the great scholars of Hellenistic antiquity. And its Jewish community was wealthy and humane and powerful and a patron of the arts. This is why Pope Benedict was right to see the LXX as a synthesis of Greek and Jewish erudition. And he was right to see this cultural marriage as "a distinct and important step in the history of Revelation". It is not without the hand of Providence that S Paul was soaked in the LXX; that Christianity rode around the Mediterranean on the back of the LXX.
One more section of this to come.