Le Guin starts her address like many other commencement speeches, thanking her audience for having her there. But then, in a curve ball of epic proportions, she reveals she's actually thanking them for the opportunity to speak as a woman.

I want to thank the Mills College Class of '83 for offering me a rare chance: to speak aloud in public in the language of women. (1)

She's not just kowtowing to social niceties; she's making her point. It's the perfect introduction to her main theme, because it makes the audience think, "Wait…what? Women have their own language?" And now she can proceed to explain what she means.