The letter arrived on a Thursday in November. It was addressed to A. Citizen, which was the pseudonym Ed had been using for his pamphlets—the name that appeared on the inside cover of the anonymous documents that were now circulating through Cambridge and the reform circles and the occasional brave soul who had found one tucked into a book in the British Museum reading room. The handwriting was careful, precise, the handwriting of a man who had learned to write carefully because he was afraid o...