How Can We Know the Dancer from the Dance?

Womantrees Dancing--Spring--- Gouache painting by Mitzi Linn

Labour is blossoming or dancing where
The body is not bruised to pleasure soul,
Nor beauty born out of its own despair,
Nor blear-eyed wisdom out of midnight oil.
O chestnut-tree, great-rooted blossomer,
Are you the leaf, the blossom or the bole?
O body swayed to music, O brightening glance,
How can we know the dancer from the dance?

from "Among School Children" by W. B. Yeats