Yeats Homework

In case anyone asks—yes, I am doing my Yeats homework. What poem is this from?

Suddenly I began,

In scorn of this audience,

Imagining a man,

And his sun-freckled face

And gray Connemara cloth,

Climbing up to a place

Where stone is dark with froth,

And the down turn of his wrist

When the flies drop in the stream—

A man who does not exist, . . .

(The Fisherman by Yeats)