Virginia Woolf doesn't look ecstatic, exactly, but she's obviously pretty pleased with herself. And why not? She's a pioneer of modernist and feminist literature. People are afraid of her. She's going to be played by Nicole Kidman some six decades after her death. And she spent most of the 1920s having an affair with Vita Sackville-West.
With all those accomplishments under your belt, and being one of the preeminent literary voices of the early 20th century, why wouldn't you raise your eyebrows and rest your head in your hand? Perhaps she's about to utter a Groucho-esque witticism. Or perhaps she's pondering her future happy plans, like taking a wade in the river Ouse with pockets full of stones. Or maybe she's thinking about the symbolism of garden parties. Whatever her thoughts, she's one happy modernist.