August 6 has a gift for endings that contain beginnings, and beginnings that contain, somewhere inside them, a kind of ending. The date does not repeat itself — no two of its significant moments share a century — but they share a structure: something that had always seemed permanent is suddenly, irreversibly gone, and something else steps into the space it occupied. On August 6, 1806, Emperor Francis II dissolved the Holy Roman Empire of the German Nation.

Every act of transmission carries a gap between what is sent and what arrives. October 29 has marked three of them — three moments in which a signal traveled from its source, and something was lost, or altered, or arrived as something entirely different from what was intended. On October 29, 1618, Sir Walter Raleigh was beheaded in the Old Palace Yard at Westminster. He had been the most glamorous figure of the Elizabethan age — explorer, poet, courtier, the man credited with introducing tobacco to England, the man who had sent two expeditions to find El Dorado and returned, each time, without it.