In his famous vision of the enthroned and exalted Lord, Isaiah is told to harden the hearts of his people, 'lest they repent' (Isa. 6.9-10). According to Mark's Gospel, which cites this text, Jesus speaks in parables for the same reason. Interpreters of all generations have, not unnaturally, found the text difficult and disturbing. This study is concerned with the fascinating variety of early Jewish and Christian interpretations and modifications...