Horace Walpole turns to the letters and argues that: Walpole's numerous letters are often used as a historical resource. In one, dating from 28 January 1754, he coined the word serendipity which he said was derived from a "silly fairy tale" he had read, "The Three Princes of Serendip". The oft-quoted epigram, "This world is a comedy to those that think, a tragedy to those that feel", is from a letter of Walpole's to Anne, Countess of Ossory, on 16 August 1776. The original, fuller version appeared in a letter to Sir Horace Mann on 31 December 1769: "I have often said,
Frances Seymour, Duchess of Somerset (1699–1754) of the Heart" (1737) was dedicated to the countess. According to Horace Walpole, Frances became interested in spiritualism, under Rowe's influence, following the death of her only son, George, who contracted smallpox in Bologna in 1744. After her husband's death in 1750, she lived her last years at Percy Lodge, where she died on 7 July 1754. She was buried with her son and husband in Westminster Abbey on 20 July. Frances Seymour, Duchess of Somerset (1699–1754) Frances Seymour, Countess of Hertford ("née" Thynne; 10 May 1699 – 7 July 1754), later the Duchess of Somerset, was a British courtier