W.B. Yeats (1865–1939). The Wild Swans at Coole. 1919.

39. Another Song of a Fool

THIS great purple butterfly,

In the prison of my hands,

Has a learning in his eye

Not a poor fool understands.

Once he lived a schoolmaster

With a stark, denying look,

A string of scholars went in fear

Of his great birch and his great book.

Like the clangour of a bell,

Sweet and harsh, harsh and sweet,

That is how he learnt so well

To take the roses for his meat.