Atbash is a simple substitution cipher for the Hebrew alphabet. It consists in substituting aleph (the first letter) for tav (the last), beth (the secon) for shin (one before last), and so on, reversing the alphabet. In the Book of Jeremiah, לב קמי Lev Kamai (51:1) is Atbash for כשדים Kasdim (Chaldeans), and ששך Sheshakh (25:26; 51:41) is Atbash for בבל Bavel (Babylon). It has been associated with the esoteric methodologies of Jewish mysticism's interpretations of Hebrew religious texts as in the Kabbalah.