"In his fifth work of nonfiction, Mark Kurlansky turns his attention to a common household item with a long and intriguing history: salt. The only rock we eat, salt has shaped civilization from the very beginning, and its story is a glittering, often surprising part of the history of humankind. A substance so valuable it served as currency, salt has influenced the establishment of trade routes and cities, provoked and financed wars, secured empires,...