Her frailty, which one can see is caused by consumption in its early stages, makes her beauty the more appealing to Rudolph.
His friends call him from the street below. Their voices draw Mimi to the window. In the moonlight she appears even lovelier to Rudolph. "O soave fanciulla" (Thou beauteous maiden), he exclaims, as he takes her to his arms. This is the beginning of the love duet, which, though it be sung in a garret, is as impassioned as any that, in opera, has echoed through the corridors of palaces, or the moonlit colonnades of forests by historic rivers. The theme is quoted here in the key, in which it occurs, like a premonition, a little earlier in the act.
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The theme of the love duet is used by the composer several times in the course of the opera, and always in association with Mimi. Especially in the last act does it recur with poignant effect.
Act II. A meeting of streets, where they form a square, with shops of all sorts, and the Café Momus. The square is filled with a happy Christmas eve crowd. Somewhat aloof from this are Rudolph and Mimi. Colline stands near the shop of a clothes dealer. Schaunard is haggling with a tinsmith over the price of a horn. Marcel is chaffing the girls who jostle against him in the crowd.
There are street venders crying their wares; citizens, students, and work girls, passing to and fro and calling to each other; people at the café giving orders—a merry whirl, depicted in the music by snatches of chorus, bits of recitative, and an instrumental accompaniment that runs through the scene like a many-coloured thread, and holds the pattern together.
Rudolph and Mimi enter a bonnet shop. The animation outside continues. When the two lovers come out of the shop, Mimi is wearing a new bonnet trimmed with roses. She looks about.