With the help of a friend, Luther hid in Wartburg Castle, near Erfurt. In the castle, he translated the Bible. First, he wrote the New Testament in German instead of the original Greek. Later, he translated the Old Testament into German, too. Until then, the Mass and the Bible were in Latin. Very few people understood it. Most people went to Mass, and did not understand what the priest said because they did not speak Latin. Luther translated the Bible so that more people could read and understand it. That way they were no longer depending on the priest to tell them what was in the Bible, but could read it themselves.