(Credit: AP Photo/Dennis Cook, File) When Ronald Reagan called the United States a “city on a hill,” in 1974, it encapsulated an expansive, optimistic vision of America. The phrase comes from a Puritan sermon by John Winthrop called “A Model of Christian Charity.” But no one knew Winthrop’s sermon existed until 1838, when it was discovered in the New-York Historical Society and printed by the Massachusetts Historical Society.