I have a problem calling this "popular myth". It may be a popular lie spread by authorities, but it is taught everywhere from church to secular school. Hardly the type of thing one refers to as a "myth" in my experience. I'll have to look into it more deeply now, as you are the first person ever to imply it is a myth that I have ever talked to. I remember specifically that a big part of the reformation as it was taught me was the right of the people to read the Bible for themselves.
Prior to the Reformation, there were Church-approved vernacular transalations in Spanish, Italian, Danish, French, Norwegian, Polish, Bohemian, and Hungarian. In English alone, we have the Anglo-Saxon translation of Caedmon of Whitby in the 600's AD, the Saxon versions of Bede of Jarrow, Eadhelm of Sherbourne, Guthlac of Peterborough, and one Egbert in the 700's AD; then the free translations of Alfred the Great and Aelfric of Canturbury, the Book of Durham, and the Rushworth Gloss from well before the Norman Conquest; the Orm Paraphrase of 1150 and the Salus Animae of 1250, and the Middle English translations of William Shoreham and Richard Rolle, both from the 1300's.
All of these, you will take note, existed centuries before John Wycliffe's flawed English translation of 1525, which was full of translationsal errors and was in fact, so bad that Henry VIII ordered eavery copy of it within the realms to located, seized, and burned. The idea that the Church kept the Bible out of the language of the people in order to keep them in the dark is a load of baloney. Were there Bibles in Latin? Sure; it was the Church's litrugical language. Were Bibles chained to pulpits in churches? Sure they were. They were copied by hand and often decorated with precious stones and metals, and ergo represented both decades of work and of extreme monetary value---they were chained up to keep thieves from stealing them---but anyone who could read was free to enter the church and read the village Bible at any time. Which brings up the point of literacy; most common people during the Middle Ages couldn't read anyway, so it really didn't matter much if their Bible was in Latin, English, German, Hindustani, or Klingon, did it? If you can't read, you can't read.
You might want to pick up a copy of
Where we Got the Bible, by Henry G. Graham (TAN Books, Rockford IL 61105), which debunks loads of these Reformations fables concernign the Catholic Church and the Bible.
As an aside, I have always understood that the reason Protestants don't accept the Deuterocanonical books is because at the time of Christ they had already been rejected by the Jews, and Christ put a stamp of approval on the Old Testament as it stood during His lifetime
The version used by most Jews in the 1st century was the Greek Septuagint, which contains the Deuterocanonicals. (Again, 90% of the OT quotes in the NT follow the Greek structure rather than the Hebrew.) The Masoretic Text, containing only the Hebrew books, was favored by the religious/political faction in Jerusalem, which included the Sadducees and the Pharisees, in part because they hated the Romans, and the Deuterocanonicals contain references to friendship treaties between the Jews and the Roman Republic in the 2nd century BC. After the destruction of Jerusalem, this religious faction met in a place called Jamnia and formalized their version of the Jewish Scriptures; they excluded the Deuterocanonicals, in no small part because the Deuterocanonicals contain a large number of prophecies which clearly point to Christ; and of course, the Christians were making use of these prophecies in application to Jesus. The Pharisaic faction in Jamnia wanted to discount the Christians and their Messiah, so they discounted these books, thus disposing of the troublesome messianic prophecies they contained.
There are more things in history than are covered in high school classes, Horatio.
Blessings and peace,
---Wols.