 Rabbi Yiḥyah founded yeshivot, rabbinical schools, and synagogues that featured a rationalist approach to Judaism based on the Talmud and works of Saadia Gaon and Maimonides (Rambam).Yeshayahu Leibowitz (1903–1994), an ultra-rationalist Modern Orthodox philosopher and brother of Nechama Leibowitz, publicly shared views expressed in Yiḥyeh Qafeḥ's book "Milḥamoth HaShem" against mysticism.For example, Leibowitz called Kabbalah "a collection of "pagan superstitions" and "idol worship" in remarks given after receiving the Yakir Yerushalayim Award (English