The Opposition of the Study of the Wisdom of Kabbalah
As long as orthodoxy insists on saying, “No! Only Gemarah and Mishnah, no legends, no ethics, no Kabbalah, and no research,” it dwindles itself. All the means it uses to protect itself, without taking the true potion of life, the Light of the Torah in its internals, beyond the tangible and obvious—the revealed in the Torah and Mitzvot—are utterly incapable of leading to its goal in all the generations, and especially in our generation, unless accompanied by expanding the many spiritual roots [in order to achieve the goal].
– Rav Kook, Igrot (Letters), Vol. 2, 232-233