In 1956, toward the end of Reverend John Ames's life, he begins a letter to his young son, an account of himself and his forebears. Ames is the son of an Iowan preacher and the grandson of a minister who, as a young man in Maine, saw a vision of Christ bound in chains and came west to Kansas to fight for abolition: He "preached men into the Civil War," then, at age fifty, became a chaplain in the Union Army, losing his right eye in battle. Reverend...