 The last letter from Haydn to Marianne is dated 13 November 1792, thus following his return to Vienna on July 24.By "my opera" Haydn meant his "L'anima del filosofo", completed the previous year; the aria in question is a lament by the main character Orpheus.The letter gives no hint at all that Marianne was ill, but in fact she died only two months later, on 26 January 1793.