Last year the Public Broadcasting System showed a Swedish movie of The Rake's Progress in which Baba was clearly a man, sung by a male alto with a short goatee. Whatever the personal sources of the character may have been, I think that Baba was Auden's way of embodying his love for the genre of opera in all its glorious absurdity. She throws the whole tidy moral universe of The Rake into confusion by showing us how dull it has grown. And not a moment too soon. Baba was Auden's joker in the pack, his way of trumping his own moral pessimism by asserting the power of art over nature.
Natural order is a recurring theme of The Rake's Progress.
She graciously renounces any claims to Tom, and thereby makes possible Anne's act of forgiveness. She's the stage mother of us all. My own fondness for Baba perhaps shows that I remain an armchair opera lover. In the theater Baba remains one of the many enigmatic features of The Rake's Progress that make it seem more like a perverse waxworks opera than like the real thing. I can describe Baba as the spirit of opera, but few directors can sell Baba to the audience, as they can easily sell the character of Zerbinetta, in Strauss's Ariadne auf Naxos, who serves a similar symbolic purpose.