“Deh vieni, non tardar” is Susanna’s aria near the end of Mozart’s Le nozze di Figaro. It’s Act IV, night, the garden. Susanna is dressed in the Countess’s clothes to trap the philandering Count Almaviva, and — she knows Figaro is hiding in the bushes watching, convinced she’s about to cheat on him.

So she sings this: oh come, don’t delay, my beautiful joy… A melting serenade apparently to a secret lover. Figaro burns. But the whole thing is a wink — the “lover” she’s actually calling is Figaro, and the aria is a real love song disguised as a fake one. Mozart lets the audience hear the sincerity that the character on stage wouldn’t allowed to.

Musically it’s almost nothing, which is the miracle. A gently rocking 6/8 in F major, pizzicato strings and a little wind trio (flute, oboe, bassoon) answering the voice like a night breeze. No fireworks, no high notes to show off. Just a long, unhurried line that a soprano can’t hide behind. It’s one of those pieces that’s hard because it’s simple.

Here’s Barbara Bonney, who is one of the great Susannas:

Listen for how little she pushes. The recitative before it — “Giunse alfin il momento” sets up the whole tease.