Mozart’s achievements in the genre of opera are unsurpassed, and no composer was better at writing ensembles than Mozart. The operas that Mozart wrote with the librettist Lorenzo Da Ponte are his greatest, and they include Don Giovanni, based on the life of the infamous Casanova, whom Da Ponte knew personally. We look at ensembles from Don Giovanni as illustrations of Mozart’s prodigious ability to sustain dynamic dramatic continuity through the power of his music. We will see, as well, how the introduction to this opera’s overture presages the grim events of the final scene.