Ch'io mi scordi di te...Non temer, amato bene is one of Mozart's great concert arias. Composed for Nancy Storace (1761 - 1817), who sang Susanna in the first performance of Le nozze di Figaro, the recitative and aria are reminiscent of Figaro, but are more akin to opera seria than anything remotely comic. By the mid-1780s, the English Storace had become the rising star in Vienna, eclipsing Aloysia Weber. Her annual salary at the Italian Opera was six times what Mozart would earn when he became engaged by the court.
Mozart's manuscript copy of Ch'io mi scordi di te is dated December 26, 1786, and the text is from an addition to Idomeneo, Act II, Scene 1, by Abate Giambattista Varesco. The piece includes an obbligato part for keyboard, which Mozart no doubt played at the premiere sometime in February 1787. Most interestingly, the obbligato contains no Alberti figures; what few of these appear in the aria are given to the strings.
The recitative of K. 505 was originally part of another scene and aria, "Non più, tutto ascoltai," K. 490, which was replaced the original opening number of Act II of Idomeneo for a private performance in March 1786. In the scene and aria for Storace, Mozart leaves out much of the recitative text and creates a more concentrated setting with characteristics more common to his chamber music. For instance, the modulation from the G minor of the recitative to the E flat major of the aria begins very early in the recitative.
The aria is marked Rondo, a form that was fashionable at the time in vocal composition. The beginning Andante segment is actually in ternary form and is introduced by the orchestra. The central, contrasting section begins at "Tu sospiri?" and modulates to the dominant. After the return of the soprano's opening lines, Mozart prepares for the shift to the faster, second part of the aria in an unusual and imaginative way. Virtually unaccompanied outbursts from the soprano ("sempre il cuorsaria," "Stella barbare," and "stella spietate!") alternate with rapid flourishes on the piano, creating an atmosphere of expectancy that allows for the most startling change in rhythm. The ensuing Allegretto is a serial rondo (ABACADA Coda). In the coda, Mozart produces the opposite of the effect he achieved in the transition when sixteenth-note scale passages in the soprano slow to eighth and then to half notes.