Aryeh Moshe Eliyahu Kaplan was an American Orthodox rabbi, author, and translator best known for his Living Torah edition of the Torah and extensive Kabbalistic commentaries. He became well-known as a prolific writer and was lauded as an original thinker. His wide-ranging literary output, inclusive of introductory pamphlets on Jewish beliefs, and philosophy written at the request of NCSY are often regarded as significant factors in the growth of the baal teshuva movement.

Kabbalah or Qabalah is an esoteric method, discipline and school of thought in Jewish mysticism. A traditional Kabbalist is called a Mekubbal. The definition of Kabbalah varies according to the tradition and aims of those following it, from its origin in medieval Judaism to its later adaptations in Western esotericism. Jewish Kabbalah is a set of esoteric teachings meant to explain the relationship between the unchanging, eternal God—the mysterious Ein Sof —and the mortal, finite universe. It forms the foundation of mystical religious interpretations within Judaism.