Pinkerton's tour of duty is over, and he has returned to the United States, after promising Butterfly to return "When the robins nest again." Three years have passed. Butterfly's faithful servant Suzuki rightly suspects that he has abandoned them, but is upbraided for want of faith by her trusting mistress. (Butterfly: "Weeping? and why?") At this point, Cio-Cio San sings one of the most repeated arias in all of opera "Un Bel Di" (One fine day) to Suzuki, where she describes the day when Pinkerton returns to her on his White Ship. Meanwhile, Sharpless has been sent by Pinkerton with a letter telling Butterfly that he has married an American wife. Butterfly (who cannot read English) is enraptured by the sight of her lover's letter and cannot conceive that it contains anything but an expression of his love. Seeing Butterfly's joy, Sharpless cannot bear to hurt her with the truth. When Goro brings Prince Yamadori, a rich suitor, to meet Butterfly, she refuses to consider his suit, telling them with great offense that she is already married to Pinkerton. Goro explains that a wife abandoned is a wife divorced, but Butterfly declares defiantly, "That may be Japanese custom, but I am now an American woman." Sharpless cannot move her, and at last, as if to settle all doubt, Butterfly, proudly presents her fair-haired child. A stirring brass fanfare accompanies his introduction. "Can my husband forget this?" she challenges. Butterfly explains that the boy's name is "Sorrow," but when his father returns, his name will be "Joy." The consul departs sadly. But Butterfly has long been a subject of gossip, and Suzuki catches the duplicitous Goro spreading more. Just as things cannot seem worse, distant guns salute the new arrival of a man-of-war, the Abraham Lincoln, Pinkerton's ship. Butterfly and Suzuki, in great excitement, deck the house with flowers, and array themselves and the child in gala dress. All three peer through shĹŤji doors to watch for Pinkerton's coming. As night falls, a long orchestral passage with choral humming (the "humming chorus") plays. Suzuki and the child gradually fall asleep - but Butterfly, alert and sleepless, never stirs.