The name "Septuagint" refers to the committee of seventy (Latin septuaginte) translators mentioned by Aristeas.
The Latin Vulgate Bible is based on a combination of Masoretic and LXX readings, but the Slavonic, Coptic, and Ethiopic versions are thought to come from the Septuagint alone. Apparently in response to its use by Christians, the LXX came under heavy fire in Jewish circles and was largely abandoned in favour of Hebrew or Syriac versions. There were a few Jewish and (curiously) Ebionite attempts to create new translations; see below.
The LXX is in some sense the "official" Orthodox Old Testament, but from the time of Origen's Hexapla until recently there seems to have been little effort to actually publish a standardized version. Ancient manuscripts and fragments differ so much from each other and from the readings in the Church's lectionary that this is something of a problem. The first "official" (hierarchically approved) printed editions, which appeared in Russia and later in Greece in the XIX Century, were essentially reprints of Western scholarly texts based on the Codex Alexandrinus and other ancient manuscripts rather than on the liturgical practice of the Church. Even now, it is not clear to us that there is a universally accepted Orthodox version based on liturgical usage.
The best English translation is very likely Michael Asser's, below. Surprisingly, this translation does not seem to be very well-known. The most widely available version is Brenton's, which, apart from any other defects, unaccountable substitutes Masoretic readings of words for the original Greek, sometimes without even a footnote. Holy Transfiguration Monastery has published a very careful translation of the Psalter, but not, apparently, of the Septuagint as a whole. Read any translation with caution, and if possible compare it to the Greek, before drawing any conclusions.
Norman Hugh Redington
Around AD 128, Aquila, a pupil of Rabbi Akiba, published an extremely literal (almost unreadable) translation of the Masoretic text in which a particular Hebrew word was always represented by the same Greek word regardless of context. This translation was often used by Christian Biblical scholars like Origen and St. Jerome as an aid in understanding the Hebrew, although it also seems to have been written expressly for use in arguments against Christians, having been comissioned for this purpose by rabbinical leaders. This version is lost except for a few fragments.
Theodotion of Ephesus wrote an extremely important translation which has a very odd history. Theodotion, who evidently was not a Jew but rather a member of the Ebionite Christian heresy (which kept kosher dietary laws), lived in the second century. His translation, however, is seemingly "quoted" in Heb. 11:33 and several times in Revelations! This strongly suggests that Theodotion's version was based upon either a lost Greek translation which competed with the LXX or upon a "revised" LXX. Amazingly, Theodotion's version of Daniel is the one officially accepted by the Church and usually printed in modern editions of the LXX; the original LXX version survives in only 3 manuscripts. The oddities connected with Theodotion's version and its use by the Church were remarked upon already by the Fathers, specifically by St. Jerome, who could offer no definitive explanation.
Late in the Second Century, another member of the Ebionite sect, Symmachus, produced a loose Greek translation, almost a paraphrase. Other Greek versions already lost in the early Christian era were rediscovered not in modern times but by the ancients: Origen published a manuscript of Job, Psalms, Song of Songs, and the Minor Prophets which someone had found in a jar near Jericho in the reign of Caracalla, and another Greek version of Psalms and some other books found accidentally in Asia Minor.
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