The poet wishes that he and his beloved could escape from their circumstances and be together. This wish is captured in the image of the two of them transformed into white birds floating on the sea-foam. He asks his beloved not to concentrate on temporal and sorrowful images - the fading meteor, the rose and lily - and reiterates his desire to be apart from the world with her, as white birds together.
Yeats composed this poem for Maud Gonne's in 1892 when the pair went for a walk along the cliffs of Howth, a seaside village just south of Dublin. The poem was written the day after Yeats had unsuccessfully proposed to her for the first time. Gonne reecalls that she said that she would rather be a seagull than any other bird. Yeats sent her this poem three days later.
The "Danaan Shore" refers to Tier-nan-Oge (or Tir na nOg in Gaelic), an imaginary land where mortals live as long as fairies. Yeats interpreted Gonne's wish to become a seagull as a wish for freedom from sorrow and time. He wishes, in vain, that they could escape the political and social circumstances that keep them apart, whether on an isolated island, in a mythic environment, or by becoming white birds.