I have linked below to the many themes of Pygmalion discussed on eNotes, including beauty, identity, appearance versus reality, and sexism. I will, however, talk about class, since that seems to me the most important theme of this play. Shaw was a Fabian, a kind of socialist who thought socialism could be brought about through reform, not by revolution. In the play, he attacks the British class system, in which the opportunities people had were based primarily on who their parents were—in other words, on the accident of birth. A class ideology or belief system insisted that people of higher class parents were genetically or innately superior to those of the lower classes, who were often thought to be born inferior or with a genetic predisposition to crime or immorality. In Pygmalion, Shaw explodes this myth of class by showing that Eliza, an impoverished flower seller, could, with a little training in how to speak and act like a lady, outshine the born aristocrats and become fit to marry a Duke (though she doesn't). Shaw also shows, in the depiction of Eliza's father, Mr. Doolittle, who comes into money, that it is economics, not birth, that determines who behaves morally according to middle-class norms.