Editing Don Carlos (section)

===Act 2===
:[This is Act 1 in the 1883 revision]
[[Image:Isabel de Valois2.jpg|thumb|The historical Elizabeth of Valois, by [[Juan Pantoja de la Cruz]], 1565]]
''Scene 1: The monastery of Saint-Just (San Jerónimo de [[Yuste]]) in Spain''

The scene takes place soon after King Philip II and Elisabeth have married. Monks pray before the tomb of the former Emperor Charles V ("Carlo Quinto"). The monks' leader proclaims that the Emperor was proud but has been humbled through error.

Don Carlos enters, anguished that the woman he loves is now his stepmother.

:[In the 1883 revision, he sings a revised version of the aria "Je l'ai vue" / "Io la vidi", which was salvaged from the omitted first act but with some different music and different text to reflect his current situation. In the four-act version he already knows that he cannot marry Elisabeth. In the original, when singing the aria, he was still expecting to marry her]

When Carlos pauses in his lament, the leader of the monks proclaims that the turbulence of the world persists even in sacred places; we cannot rest except in Heaven.  The sound of his voice frightens Carlos, who thinks it sounds like that of the Emperor Charles V. Carlos further notices that the monk physically resembles the Emperor, and recalls hearing rumors that the Emperor's ghost haunts the monastery.

Carlos' dear friend Rodrigue, Marquis of Posa, who has just arrived from the oppressed land of Flanders, enters.  The two greet each other joyfully (Aria: "J'étais en Flandres").

Rodrigue asks for the Infante's aid on behalf of the suffering people there. Carlos reveals that he loves his stepmother. Rodrigue is first shocked, but then sympathetic.  He encourages Carlos to leave Spain and go to Flanders, and to forget his pain by focusing on political activity there. The two men swear eternal friendship (Duet: "Dieu, tu semas dans nos âmes" / "Dio, che nell'alma infondere").

King Philip and his new wife, with their attendants, enter also to do homage at Charles V's tomb, while Don Carlos laments his lost love.

''Scene 2: A garden near Saint-Just''
[[File:Un sito ridente alla porte del Chiostro di S. Giusto, bozzetto di Carlo Ferrario per Don Carlo (1884) - Archivio Storico Ricordi ICON000097.jpg|Set design by [[Carlo Ferrario (painter)|Carlo Ferrario]] from the première of the Milan version, Act I, Scene 2 (Act II, Scene 2 in the unrevised version)|thumb|upright=1.4]]
Princess Eboli sings the Veil Song ("Au palais des fées" / "Nel giardin del bello") about a Moorish King trying to seduce an alluring veiled beauty, who turns out to be his own neglected wife. Elisabeth enters. Rodrigue gives her a letter from France, which covers a secret note from Don Carlos. At his urging (Aria: "L'Infant Carlos, notre espérance" / "Carlo ch'è sol il nostro amore"), Elisabeth agrees to see the Infante alone. Unaware of this relationship, Eboli infers that she, Eboli, is the one Don Carlos loves.

When they are alone, Don Carlos tells Elisabeth that he is miserable, and asks her to request the King to send him to Flanders. She promptly agrees, provoking Carlos to renew his declarations of love, which she piously rejects. Don Carlos exits in a frenzy, shouting that he must be under a curse. The King enters and becomes angry because the Queen is alone and unattended.  His suspicions are insulting to her. He orders the lady-in-waiting who was meant to be attending her, the Countess of Aremberg, to return to France, prompting Elizabeth to sing a sorrowful farewell-aria. (Aria: "Oh ma chère compagne" / "Non pianger, mia compagna").

The King now approaches Rodrigue, with whose character and activism he is impressed, and offers to reward him for his loyalty and service. Rodrigue begs the King to stop oppressing the people of Flanders. The King calls Rodrigue's idealism unrealistic and warns that the Grand Inquisitor is watching him. The King confides in Rodrigue, telling him that he fears that Carlos is having an affair with Elisabeth.  Rodrigue replies that Carlos is innocent, and offers to watch Elisabeth and to be responsible for her good behavior.  The King gratefully accepts this offer, and again warns Rodrigue to beware of the Grand Inquisitor.

:[This dialogue was revised three times by Verdi.]
[[Image:La princesa de Éboli.jpg|thumb|The historical Princess of Eboli, Ana de Mendoza, by unknown artist]]