To paraphrase a Swiss scholar: “When angels in heaven are at work, making music to the greater glory of God, they play Bach.  But when they are at home, they play Mozart.”

I wager that while those angels are commuting, they sing “E nel tuo, nel mio bicchiero” from Mozart’s Cosi fan tutte.

Cosi is a late opera, first performed in January 1790, less than two years before the composer’s death.  It is the third and last opera that Mozart composed in partnership with the librettist Lorenzo da Ponte.

The plot is feather light.  Fiordiligi (soprano) and her sister Dorabella (mezzo) are in love with two dashing soldiers, Guglielmo (bass) and Ferrando (tenor).  The men idolize the women, so much that they accept a bet from an old cynic, Don Alfonso, who claims that he can prove the sisters, like all women, have feet of clay. (Cosi fan tutte – All women are like that.)

With the approval of the two friends, Alfonso prepares his trap.  He tells the ladies that their lovers have been called to war.  (At no point do the sisters ask when the war started, what caused it, who the enemy is.)  The men sail away.  Don Alfonso then introduces two Albanian gentlemen to the ladies.  To spare you the suspense, these Albanians are Guglielmo and Ferrando in disguise.

Each Albanian tries to win the affection of the sister whose heart belongs to his friend.  Guglielmo proceeds to seduce Dorabella, who gives in with no more than a token struggle.  Ferrando has a lot more trouble winning the affections of Fiordiligi.  Her resistance produces two magnificent arias, one in each of the two acts, but eventually she gives way.

The two couples sign marriage contracts.  (When local law forbade presenting religious ceremonies on stage, librettists used marriage contracts to get the idea across.)  At that moment, Fiordiligi lifts her glass in a toast to drown bitter memories – the loss of old lovers, the struggle to deny new ones – and to celebrate the sweet surrender at battle’s end.

Her words – “And in your glass and mine – E nel tuo, nel mio bicchiero — may every thought be drowned and may no memory of what is past remain in our hearts” (like most operatic texts, it sounds better in Italian) – are sung to a melody of ethereal beauty, a gentle arc lightly decorated and anchored by sustained notes.  Mozart’s ability to address the nerve endings in our skin by tightening and releasing tension in each measure and each phrase of his music is on full display in this number.

As Fiordiligi finishes the first phrase of her toast, as the audience is transported by the beauty of the moment, Mozart adds to the magic.  Ferrando joins Fiordiligi, starting the melody from the beginning as she moves to the next strain.  The two sing in counterpoint, each voice enhancing the beauty of the other.  As Ferrando finishes the first phrase, Dorabella joins in.  Now three voices gently entwine with each other.

The effect is otherworldly.  As Dorabella finishes the first phrase of her song, the orchestra and singers prepare us for Guglielmo to join in so that we can hear this lovely melody sung as a perfect canon in four voices.  At this climactic moment, Mozart reminds us that this stunning beauty is in service to an illusion.  The ladies are toasting weddings that are not going to take place, memories that are not going to be drowned.

Mozart was not only a great composer.  He was a master psychologist and dramatist.  He has more to do than express the happiness of lovers about to be married.  Ferrando took up Fiordiligi’s song because he was overwhelmed by the moment, even though he must know further back in his mind that the toast is an illusion and that he will soon return to Dorabella (if she will have him).  Not so Guglielmo.  He does not provide the canon’s fourth voice.  He sees things for what they are.   In a raw melody with no effort to blend in with the three voices above his, he sings “I wish those bitches were drinking poison.”

The number takes only two minutes to perform but it encapsulates the power of Cosi.  The plot is so light that a gentle breeze would blow it away.  The audience cannot simply suspend disbelief; we have to leave it outside the theater door.  Yet this thin story, thanks to Mozart’s magnificent music, puts the four lovers and their supporting players under the microscope in ways that more serious and more realistic tales too often fail to do.  The opera ends with the lovers paired as they were at the beginning.  The couples have been rejoined; we can doubt that they are reunited.

The best way to hear the piece is in context, as part of the entire opera.  Wikipedia lists more than thirty recordings in an entry titled “Cosi fan tutte discography.”  I like the 1962 recording with Karl Böhm conducting and Elizabeth Schwarzkopf as Fiordiligi, but I doubt that there is a bad recording. YouTube offers five full-length video presentations.  The opera deserves to be seen as well as heard, so one of these might serve, and the price is right.

If you want to hear the two-minute piece on its own, search “e nel tuo, nel mio” on YouTube to find half a dozen or so selections.  If you choose one of the video presentations, do invest two more minutes and listen to the Böhm-Schwarzkopf sound recording.  The conductor and singers were all major artists in their day and provide a perfect ensemble.  Music to see an angel home after a long day at work.