The great thing about myth is that it's not absolute. You can keep riffing. Artists who want to revolutionize their art forms are tempted by myth because they want something that's already abstracted from ordinary experience. Myth is expansive and suggestive rather than concrete. The stories are about things other than what they look like they're about. Myth takes human experience to an archetypal level.

What did Strauss respond to in the story of Helen of Troy?

Die ‹gyptische Helena is actually based on the Euripides play Helen, in which she didn't really go to Troy; she's in Egypt. The opera is a kind of secondhand recounting of Euripides's fanciful rewriting of a myth. What Strauss and von Hofmannsthal are doing is speculating about the spaces in between the myths. That's what the Greek tragedians did. There wasn't a master text that you had to obey. You could just decide, 'Well, in this version, I'm going to have Helen not go to Troy — it's just a phantom that went to Troy, and the real Helen is in Egypt waiting to be rescued.' It's seeing how far they can push the boundaries. And of course Strauss also does that musically.

The Met is staging Gluck's Orfeo ed Euridice this spring. Why are composers so interested in the Orpheus myth? And why do audiences love it?

Orpheus is the preeminent figure of the musician in Western myth. He's the creative artist who uses words and sounds, so he's particularly suited to opera, which is, of course, not just music but also words. One of the few things that contemporary artists have in common with classical artists is a fund of stories that everyone already knows. Audiences are attuned to judging how a particular story is going to be used by a particular artist to make his particular point. We already know how the story ends. That's where the fun begins.

Is this why audiences are drawn to particular operas repeatedly?

Do we really think that maybe Violetta won't die? No, we want to see how this production does it. That's why the explosion of directorial influence in the past generation is so interesting — it acknowledges that these stories have assumed the status of myths — they are a known quantity that can then be stretched. It's a cultural inheritance that people understand.

Next season the Met stages Gluck's Iphig_nie en Tauride for the first time since 1917.

Like Strauss's Egyptian Helen, it's an opera based on a late Euripides drama that's also a kind of riff on established tradition. Agamemnon had to send his fleet to Troy, but there were no winds. He sacrificed his daughter to appease the goddess of the winds, they sailed to Troy, and that's why Clytemnestra later kills him. There — you have the whole Oresteia in two sentences. It's the same kind of question as in Helen: What if she wasn't really killed? If, at the moment the knife was about to slit her throat, she was bodily transported to the other end of the world? And then it imagines the life of this girl far from home, trying to get home, forced to be the evil priestess. It's a wonderful opera!