Rabbi Aryeh Moshe Eliyahu Kaplan was born on 14 Cheshvan 5695 (1934) in the Bronx, New York, as Leonard Martin Kaplan, the son of Samuel and Fannie Kaplan, of a Sephardic family from Salonika; he lost his mother at thirteen. He studied in yeshivot, was ordained at the Mir yeshiva, and also earned a master's degree in physics before devoting himself entirely to writing and teaching.

A leading figure of the return-to-tradition movement in the United States, he published more than 50 books in some fifteen years, including many pamphlets on Jewish belief and thought written for the NCSY youth movement. He wrote The Living Torah, an annotated translation of the Torah, works on Jewish meditation and Kabbalah (Meditation and Kabbalah, Jewish Meditation, translations of Sefer Yetzirah and the Bahir), the English translation of Me'am Lo'ez, and many books on Rebbe Nachman of Breslov. His writings strongly shaped the development of modern Jewish meditation.

His books brought countless distant Jews back to their tradition. He died suddenly at 48, on 14 Shevat 5743 (1983), leaving a wife and nine children, and rests on the Mount of Olives.