Don Giovanni (1787) is a version of the Don Juan story penned by librettist Lorenzo da Ponte. The anti-hero is a nobleman who takes advantage of his social position to seduce or rape many hundreds of women and girls (the current count, according to his servant Leporello, is 2,065) in Italy, Germany, France, Turkey, and Spain. Early in the opera, Giovanni comes upon a procession celebrating the upcoming marriage of two peasants named Masetto and Zerlina, and sets his sights on the bride. He gets rid of all the others and begins seducing Zerlina, who is tempted by his attentions but fears that he will leave when he has had his way with her. He promises that in his nearby casinetto (little villa) he will change her sorte (fate), by making her a nobleman's wife:

Don Giovanni Là ci darem la mano, là mi dirai di sì. Vedi, non è lontano; partiam, ben mio, da qui. Zerlina (Vorrei e non vorrei; mi trema un poco il cor. Felice, è ver, sarei, ma può burlarmi ancor.) Don Giovanni Vieni, mio bel diletto! Zerlina Mi fa pietà Masetto. Don Giovanni Io cangerò tua sorte. Zerlina Presto, non son più forte! Don Giovanni Vieni! Vieni!   Là ci darem la mano. Zerlina Vorrei e non vorrei. Don Giovanni Là mi dirai di si. Zerlina Mi trema un poco il cor. Don Giovanni Partiam, ben mio, da qui. Zerlina Ma può burlarmi ancor. Don Giovanni Vieni, mio bel diletto! Zerlina Mi fa pietà Masetto. Don Giovanni Io cangerò tua sorte. Zerlina Presto, non son più forte! Don Giovanni Andiam'! Zerlina Andiam'! Giovanni and Zerlina Andiam', mio bene, a ristorar le pene  d’un innocente amor!

There you will give me your hand, there you will tell me “yes.” You see, it is not far; Let's go from here, my beloved. (I would like to, and I wouldn't. My heart trembles a little. I would be happy to, it's true, but he may be tricking me.) Come, my beautiful love! I feel sorry for Masetto. I will change your fate. Soon I won’t be strong anymore! Come! Come! There you will give me your hand. I would like to, and I wouldn't. There you will tell me “yes.” My heart trembles a little. Let's go from here, my beloved. But he may be tricking me. Come, my beautiful love! I’m sorry for Masetto. I will change your fate. Soon I won’t be strong anymore! Let's go! Let's go! Let's go, my beloved, to relieve the pangs of an innocent love!

There is nothing "innocent" about Giovanni's pangs, and Boylan seems cast in the same mold, but Molly is hardly innocent herself. She sees how the song bears on her marital situation and feels justified in taking some pleasure outside of a marriage lacking in sexual satisfaction: "I know what Ill do Ill go about rather gay not too much singing a bit now and then mi fa pieta Masetto then Ill start dressing myself to go out presto non son piu forte Ill put on my best shift and drawers let him have a good eyeful out of that to make his micky stand for him Ill let him know if thats what he wanted that his wife is fucked yes and damn well fucked too up to my neck nearly not by him 5 or 6 times...serve him right its all his own fault if I am an adulteress as the thing in the gallery said O much about it if thats all the harm ever we did in this vale of tears God knows its not much doesnt everybody only they hide it."

Although Molly finds much to dislike about Boylan after spending intimate time with him, she does not seem to have experienced any of Zerlina's prior hesitation. When Bloom recalls Zerlina's first line in Calypso he misremembers it in a way that emphasizes his wife's very active participation in the adulterous liaison: "Voglio e non vorrei. Wonder if she pronounces that right: voglio." Substituting the present indicative voglio ("I want") for the conditional vorrei ("I would like") calls the reader's attention to Molly's very active desire. In the next chapter, Lotus Eaters, even the one conditional verb has dropped out: "Voglio e non." But one chapter after that Bloom does recall the line correctly: "voglio e non vorrei. No: vorrei e non."

It is a joke with multiple layers. Not only is Molly's pronunciation of the word irrelevant, since it does not appear in the duet, but voglio has a particular, unflattering application to Bloom himself. His counterpart in the seduction scene is the subjugated Masetto, and he outdoes Masetto in abjectness. Masetto in fact stands up for himself, trying in vain to stop the rapacious nobleman from exercising his droit de seigneur. Bloom never does, and his substitution of voglio connects him with Don Giovanni's servant Leporello, as Robert M. Adams has suggested (Surface and Symbol, 71). In a deliciously mock-heroic aria at the beginning of the opera, "Notte e giornio faticar," Leporello dreams of throwing off the yoke of servitude and becoming a master himself. The rousing central declaration of this aria is "Voglio far il gentiluomo, / E non voglio più servir": "I want to play the gentleman, / And I don't want to serve anymore." But at the end of the opera, after Giovanni has died, he goes looking for "a better master," as much a servant as ever.

It makes perfect sense for Bloom to identify with Leporello, as with Masetto. Calypso shows him to be a servant to his wife, and in Circe his failure to stand up to the violator of his marriage is enacted by having him serve Boylan as a butler, showing him into the house and conducting him to the room where Molly is stepping naked out of her bathtub. A phrase in Ithaca, "supraracial prerogative," suggests that he acquiesces in the violation of his marriage in part because his Jewish heritage puts him in an inferior position to the ethnically Irish Boylan, like a peasant displaced by an aristocrat.

Bloom tries to turn the tables, in fantasy, when he woos his former flame Josie Breen in Circe. With "his fingers and thumb passing slowly down to her soft moist meaty palm which she surrenders gently," he places on her finger a ring that signifies domination more than betrothal, and says, "Là ci darem la mano." She replies with the same misremembered phrase that implied sexual excitement in Lotus Eaters: "Voglio e non. You're hot! You're scalding!" But, as Stephen says of Shakespeare's whoring in London, such "Assumed dongiovannism" cannot dispel the pain of being betrayed. In his introduction to Hades in James Joyce's Ulysses: Critical Essays, Adams observes that Bloom's recollection of another line from the song, "Mi trema un poco," stops just short of articulating "il core," the heart, which would add romantic heartbreak to all the other thoughts of broken hearts in the chapter (105).

Other threads from Don Giovanni weave their way into Ulysses starting in Lestrygonians, when Bloom recalls the scene from the end of the opera in which the seducer is finally caught and punished. These details center on the image of feasting.