Paris, in the 1830s, among the young and broke. On Christmas Eve the poet Rodolfo, alone in his freezing garret, answers a knock: his neighbor Mimì, a seamstress, whose candle has gone out. They fall in love in about fifteen minutes of music, which you will believe completely. Their friends, the painter Marcello and his on-again, off-again Musetta, quarrel merrily at a café. But Mimì is ill with consumption; Rodolfo, unable to help her and unable to bear watching, drives her away; and in the last act she is brought back to the garret to die among her friends, her cold hands in a muff Musetta went out to buy for her, while the philosopher Colline goes off to pawn his old overcoat.

Listen for: the two arias in which they introduce themselves to each other in Act I, his ("Che gelida manina," your tiny hand is frozen) and then hers ("Sì, mi chiamano Mimì"), and the duet that follows; Musetta's waltz in Act II; and the way the tunes from Act I come back, quietly, at the end. If you do not cry, see a doctor.

Seville. Don José, a corporal with a sweetheart back home, is undone by Carmen, a worker at the cigarette factory who does exactly what she pleases. He lets her escape arrest, is jailed for it, deserts the army for her and follows her into the mountains with a band of smugglers. She tires of him, as she tires of everyone, and takes up with the bullfighter Escamillo. Outside the bullring, while the crowd cheers Escamillo inside, José begs Carmen to come back. She refuses, and throws his ring at him, and he kills her. Bizet died three months after the premiere, thinking it had failed.

Listen for: the Habanera ("L'amour est un oiseau rebelle"), which is Carmen's entire philosophy in three minutes; the Toreador Song; José's Flower Song; and the fate motive, a menacing little phrase in the orchestra that you hear in the prelude and then whenever things are about to go wrong. It is the best-known opera in the world for good reason.

A fairy tale, with spoken dialogue between the numbers. Prince Tamino is saved from a serpent and sent by the Queen of the Night to rescue her daughter Pamina from the high priest Sarastro, who the Queen says is a villain. Tamino gets a magic flute; his companion, the bird-catcher Papageno, who would rather have a wife and a glass of wine than an adventure, gets magic bells. It turns out Sarastro is the wise one and the Queen the villain, and Tamino and Pamina must pass trials of silence, fire and water to be worthy of each other. Papageno, who fails every trial, gets his Papagena anyway, because Mozart loved him. Mozart died two months after the first performance.

Listen for: the Queen of the Night's second aria, with those high staccato notes that sound like no human voice should be able to produce them; Papageno's folk-like songs; Sarastro's deep, calm bass arias; and the little duet near the end where Papageno and Papagena can only stammer "Pa-pa-pa" at each other. Take a child.

A comedy, and the funniest thing in the repertory. Count Almaviva loves Rosina, the ward of old Doctor Bartolo, who intends to marry her himself for her money. The Count enlists Figaro, the town barber and fixer of everything, and spends the opera in disguise: as a poor student, as a drunken soldier, as a substitute music teacher. Bartolo's ally, the music master Basilio, suggests slander as a strategy. Notes are passed, a ladder appears at a window, and the Count and Rosina are married under Bartolo's nose. The same characters, a few years older, appear in The Marriage of Figaro (number 10).

Listen for: the overture; Figaro's entrance aria "Largo al factotum" (the "Figaro, Figaro, Figaro" one, which you already know); Rosina's "Una voce poco fa"; the slander aria, which starts as a whisper and grows to a cannon shot; and the Act I finale, where the whole cast sings about how confused they are, in perfect order.

Nagasaki, around 1900. Pinkerton, a lieutenant in the United States Navy, marries a fifteen-year-old geisha, Cio-Cio-San, called Butterfly, under a Japanese contract he regards as a convenience and she regards as sacred. He sails away. She waits three years, with their little son, refusing every suggestion that he is not coming back. He does come back, with an American wife, to take the child. Butterfly gives up the boy, blindfolds him, and kills herself with her father's sword. It is the hardest of the ten to watch, and the most beautiful.

Listen for: the long love duet that closes Act I; "Un bel dì" (one fine day), in which Butterfly describes, in detail, the return she is certain of; the Humming Chorus, sung offstage while she keeps watch all night; and Puccini's use of Japanese melodies and, for Pinkerton, a few bars of "The Star-Spangled Banner."

Rigoletto is the hunchbacked jester at the court of the Duke of Mantua, a charming and heartless seducer, and he earns his keep mocking the Duke's victims. One of them, an old nobleman whose daughter the Duke has ruined, curses him. Rigoletto has a secret: a daughter, Gilda, whom he keeps hidden and adores. The courtiers, thinking she is his mistress, kidnap her for the Duke. Rigoletto hires an assassin, Sparafucile, to kill the Duke; but Gilda, who loves the Duke in spite of everything, overhears the plan and takes his place. Rigoletto opens the sack expecting the Duke's body and finds his daughter, dying, and the curse is fulfilled.

Listen for: Gilda's "Caro nome"; the Duke's "La donna è mobile," the catchiest tune ever given to a villain, which Verdi kept from the cast until the last rehearsal so it would not leak out before opening night; and the great quartet in the last act, in which the Duke flirts, the assassin's sister laughs him off, Gilda weeps and Rigoletto plots, all at the same time.

Rome, June 1800, in one day. The painter Cavaradossi hides an escaped political prisoner. His lover, the famous singer Floria Tosca, is jealous and devout and easily played, and the chief of police, Baron Scarpia, plays her: he arrests Cavaradossi, has him tortured within her hearing, and offers Tosca a deal: herself in exchange for her lover's life, with a "mock" execution to make it look real. She agrees, and then stabs Scarpia with his own dinner knife. At dawn Cavaradossi faces the firing squad; Tosca tells him to fall convincingly; the execution is not mock; and she leaps from the parapet of the Castel Sant'Angelo. Three acts, three deaths, no wasted time.

Listen for: the three brutal chords that open the opera and mean Scarpia; Cavaradossi's two arias, "Recondita armonia" and, before the execution, "E lucevan le stelle"; Tosca's "Vissi d'arte," in which she asks God why He is doing this to her; and the end of Act I, where Scarpia plots her seduction over a church full of people singing a Te Deum.

The Don Juan story. Don Giovanni, a nobleman who has seduced, by his servant Leporello's count, 2,065 women in five countries, is surprised in the bedroom of Donna Anna, and kills her father, the Commendatore, in a duel. The rest of the opera is his pursuit by Anna and her fiancé, by Donna Elvira, whom he abandoned and who cannot stop loving him, and by a peasant, Masetto, whose bride Zerlina he tries to seduce on her wedding day. Giovanni escapes them all. What he cannot escape is the stone statue on the Commendatore's tomb, which he mockingly invites to dinner. It comes. It offers him one last chance to repent; he refuses; and it drags him down to hell.

Listen for: the overture, whose opening is the statue's music; Leporello's Catalogue Aria, in which he reads the list to Elvira; "Là ci darem la mano," the seduction duet with Zerlina, so lovely you almost side with him; and the arrival of the statue, with trombones, which is the most frightening minute in Mozart.

Ancient Egypt. Aida, an Ethiopian princess captured and enslaved, is the servant of the Egyptian princess Amneris. Both women love the young general Radamès, who loves Aida. Radamès leads Egypt to victory over Ethiopia and returns in triumph with prisoners, one of whom is Aida's father, the king Amonasro, in disguise. Amonasro forces Aida to get the Egyptian army's route out of Radamès, who, realizing he has betrayed his country, gives himself up. He is condemned to be sealed alive in a vault beneath the temple. Aida has hidden herself inside to die with him, while above them Amneris prays. It was written for the opera house in Cairo and is the grand opera with elephants, if the company can afford elephants. Most cannot.

Listen for: "Celeste Aida," the tenor's aria five minutes into the evening, which is famous for being cruelly difficult so early; the Triumphal March in Act II, with its long trumpets; Aida's "O patria mia" by the Nile; and the final duet in the tomb, which is as quiet as the march is loud.

One mad day in the castle of Count Almaviva, the same Count from The Barber, now married to Rosina and bored with her. His valet, Figaro, is marrying the Countess's maid, Susanna, today, and the Count, who has renounced the old feudal right to the bride, would rather like to un-renounce it. Figaro, Susanna and the Countess plot to catch him. Complicating everything is the page Cherubino, a teenage boy (sung by a woman) in love with every female in the building, who keeps having to be hidden in closets and thrown out of windows. It ends in the garden at night, everyone disguised as everyone else, with the Count caught red-handed and asking his wife's pardon. She gives it. The music at that moment is the reason people say Mozart understood human beings better than anyone.

Listen for: the overture, four minutes of pure fizz; Figaro's "Non più andrai," teasing Cherubino about army life; Cherubino's "Voi che sapete"; the Countess's two sad arias; the "letter duet" for Susanna and the Countess; and the finale of Act II, twenty minutes in which the number of people on stage keeps growing and the music never stops.