"The Touchstone" is a novel by Edith Wharton that follows the character Stephen Glennard, a young lawyer who is struggling financially. When he discovers a stash of letters from a famous deceased author, Mrs. Margaret Aubyn, who was secretly in love with him, he decides to sell them in an attempt to make money, despite ethical concerns. The book explores themes of guilt, deceit, and the moral consequences of Glennard’s choice, especially after marrying the unsuspecting woman who bought the letters.