With these words to Boswell, Samuel Johnson dismissed Lady Di Beauclerk, the wife of one of his closest friends, a woman of the highest rank, the daughter of a duke, who had forsaken her reputation, her place in society, her children, and her role as lady-in-waiting to the Queen for love. Born Lady Diana Spencer in 1735, the eldest child of the third Duke of Marlborough, she was expected rigidly to follow a traditional path through life: educated...