God Hidden, Whereabouts Unknown: An Essay on the 'Contraction' of God in Different Jewish Paradigms
Rabbi Zalman Schachter-Shalomi, the founder of the Jewish Renewal movement, is widely considered one of the world's foremost authorities on Hasidism and Kabbalah.  Netanel Miles-Yépez is a scholar of comparative religion, and co-founder of the Inayati-Maimuni Tariqat, which fuses Sufi and Hasidic principles of spirituality.