Stephen L. Sass's The Substance of Civilization shows that the story of human civilization can be read most deeply in the materials we have found or created, used or abused. They have dictated how we build, eat, communicate, wage war, create art, travel, and worship. Some, such as stone, iron, and bronze, lend their names to ages. Others, such as gold, silver, and diamond, contributed to the rise and fall of great empires. How would history have unfolded without glass, paper, steel, cement, or gunpowder? Sass shows us how substances and civilization have evolved together. In antiquity, iron was considered more precious than gold. Spanish miners in the New World thought platinum, which is more rare than silver, a useless nuisance. The celluloid used in movie film had its origins in the search for a substitute for ivory billiard balls. The discovery ages ago that clay could be fired to make pots was revolutionary; so was the more recent discovery that clay also contains the substance that runs our computers.