Wollstonecraft's novel, Frankenstein, or The Modern Prometheus, was published about this time in 1818. Even though Wollstonecraft was only twenty at the time she wrote the novel, it was both a popular and critical success, and continues to be represented in film and theater productions. Many interpretations of the novel exist, but when viewed in terms of Wollstonecraft's life, the story depicts the cruelty of a society that persecutes outcasts. When Clara died on a trip to Italy, Wollstonecraft blamed her husband. However, the birth of Percy Florence in 1820 lifted her spirits. Percy was the only Shelley/Wollstonecraft child who survived. In 1822, days before Shelley's thirtieth birthday, he drowned while sailing his boat the Don Juan. Mary edited his Posthumous Poems and Poetical Works for publication in 1824 and 1839, respectively. Although her finances were secure after she received the inheritance of her father-in-law,Timothy Shelley, she did not have the strength to complete a planned project of her husband's biography.