Make the heart of this people dull, and their ears heavy, and blind their eyes; lest they see with their eyes, and hear with their hearts and turn and be healed. This call of the prophet Isaiah in Isaiah 6 has perplexed readers of all times. Torsten Uhlig reconsiders this text and other related passages. Applying a communicative approach and engaging with recent studies on righteousness, the author presents a new interpretation of the theme of hardening in the Book of Isaiah. He argues that hardening is to be understood in the context of the communicative aspect of righteousness and elucidates the communicative acts involved in the hardening of the people. Describing the role of these passages within the communicative strategy of larger units, this monograph offers a distinctive contribution to the interpretation of the Book of Isaiah as a whole.