What were the problems that troubled the Kotzker during his last twenty years, which he spent in seclusion ? No answer can be posited with certainty. From his utterances on those occassions when he left his chamber, we can only surmise that he was tormented by the ever-present enigma: why did God permit evil in the world ?

A.J. Heschel, A Passion for Truth , Jewish Lights Publishing, p. 263