Varenka's history, and the Italian song

The Princess learns Varenka's history. Madame Stahl, divorced and sickly, lost her first baby at birth; her relations, fearing the news would kill her, substituted a child born the same night in the same Petersburg house, the daughter of a palace chef. Madame Stahl later learned the truth and brought Varenka up anyway. She has lived abroad in the South for over ten years, scarcely leaving her bed, on friendly terms with highly-placed personages of every denomination while nobody knows which is hers. Invited to sing, Varenka goes straight to the piano, sings admirably at sight with Kitty accompanying, and is wholly indifferent to the crowd that gathers under the window. Asked to skip an Italian song, she changes her mind and sings it as coldly and well as the rest; in the garden she explains that she once loved a man who sang it with her, and whose mother married him to another. Kitty asks what is important. Varenka does not understand the question, and goes home alone.

Kitty asks the novel's own question — what is important — and Tolstoy denies her an answer twice over: Varenka says 'many things' without knowing what she means, then leaves for Madame Berthe's. The swapped babies give Varenka a life with no given place in it, which is the source of the tranquillity Kitty envies and cannot copy.