While the greatest, minds of the Jewish and Christian worlds have realized that the Bible is a book of allegories, few seem to have taken the trouble to investigate its symbols and parables. When Moses instituted his Mysteries, he is said to have given to a chosen few initiates certain oral teachings which could never be written but were to be preserved from one generation to the next by word-of-mouth transmission. Those instructions were in the form of philosophical keys, by means of which the allegories were made to reveal their hidden significance. These mystic keys to their sacred writings were called by the Jews the Qabbalah (Cabala, Kaballah).
-Manly P. Hall - The Secret Teachings of all Ages
Image: Tree of Life from Syriac New Testament, Vienna 1555