"" (K. 418) is a soprano aria by Wolfgang Amadeus Mozart. History Mozart entered the aria into his catalogue on 20 June 1783 Vienna. It was performed in the Burgtheater, Vienna, on 30 June 1783, as an insertion aria for a performance of Pasquale Anfossi's opera Il curioso indiscreto which had premiered with great success in 1777 in Rome. Mozart wrote two other insertion arias for that occasion, "No, che non sei capace" (I. 7) (K. 419) and "Per pietà, non ricercate" (II. 4) (K. 420); K. 418 and K. 419 were written for Mozart's sister-in-law Aloysia Weber, K. 420 for Valentin Adamberger, but that aria was not performed because of some intrigue initiated by Salieri. The aria is part of the 1991 pasticcio opera The Jewel Box. Music "" was written as a draft for this work just a few days before; it resembles more a piano reduction than a genuine work for piano and soprano. For the final version, the text of the first slow section was changed considerably. The aria is scored for oboe I and II, bassoon I and II, horn I in D, horn II in A, and strings. The work is 151 bars long and takes about seven minutes to perform. The key signature is A major. The aria is divided into three parts; the first part with a time signature of alla breve and a tempo direction of adagio, ends in bar 80 after a reprise of the initial stanza. The second part is in the time signature of common time and a tempo indication of allegro; at bar 124, the tempo accelerates to più allegro to the words of the last stanza. The aria has a vocal range of 2 octaves plus a fourth (or 2 900 cents), from E6 to B3; the latter note is a whole note in bar 135, followed immediately by a whole note D6, an interval of 2 octaves plus a minor third. Libretto Giovanni Bertati is often given as the author of the opera's libretto, others credit Giuseppe Petrosellini; however, neither is confirmed. The aria is inserted at the end of act 1, scene 6, where Marchese Calandro wants to test his bride's Clorinda's fidelity – six and a half years later, in 1790, this was a central theme in Mozart's opera Così fan tutte. Calandro persuades his friend, Count di Ripaverde, to court Clorinda. At