 They objected to Maimonides equating the Talmudic Maaseh Breishit and Maaseh Merkavah secrets of the Torah with Aristotelean physics and metaphysics in that work and in his legal Mishneh Torah, teaching that their own Theosophy, centred on an esoteric metaphysics of traditional Jewish practice, is the Torah's true inner meaning.The Kabbalist medieval rabbinic sage Nachmanides (13th century), classic debater against Maimonidean rationalism, provides background to many kabbalistic ideas.An entire book entitled "Gevuras Aryeh" was authored by Yaakov Yehuda Aryeh Leib Frenkel and originally published in 1915, specifically to explain and elaborate on the kabbalistic concepts addressed by Nachmanides in his classic commentary to the Five books of Moses.