Denis Donoghue turns his attention to the practice of metaphor and to its lesser cousins, simile, metonym, and synecdoche. Metaphor ("a carrying or bearing across") supposes that an ordinary word could have been used in a statement but hasn't been. Instead, something else, something unexpected, appears. The point of a metaphor is to enrich the reader's experience by bringing different associations to mind. The force of a good metaphor is to give...