“In America today, age is the modality in which class is lived,” writes Samuel Moyn, the Yale University professor of law and history, in his new book, Gerontocracy in America. As he acknowledges, the phrase is a riff on Marxist cultural theorist Stuart Hall’s famous statement that class is lived through race. The repurposing is pithy and striking—though it’s also quietly evasive. Is Moyn saying that age is another modality through which class is lived?