At some point during the early history of rabbinic Judaism there emerged a tripartite Hebrew Bible known by the Hebrew acronym TaNak, which stands for Torah, Neviim, Ketuvim, that is, Pentateuch, Prophets, Writings. This was similar to but different from the first testament of the double testament Greek Bibles being used at the same time in Christian communities throughout the Graeco-Roman world. Several canons of Christian Scripture of differing contents exist, ranging from the eighty-one-book Ethiopian Orthodox canon to the sixty-six-book Protestant canon. A number of references in ancient Jewish literature indicate the beginning of the Jewish tripartite canon, starting with the Torah and the Prophets. A tenet of rabbinic Judaism that separated it from other forms of Judaism was the rabbinic belief that prophecy or divine revelation/intervention in history ceased in the Persian period. Adaptability and stability must balance each other for the canonical process to be effective.