This is a poem by Fiona Macleod, a pseudonym for William Sharp who included this poem in his play, The Immortal Hour.
How beautiful they are,
The lordly ones
Who dwell in the hills,
In the hollow hills.They have faces like flowers
And their breath is wind
That blows over grass
Filled with dewy clover.Their limbs are more white
Than shafts of moonshine:
They are more fleet
Than the March wind.They laugh and are glad
And are terrible:
When their lances shake
Every green reed quivers.How beautiful they are,
How beautiful,
The lordly ones
In the hollow hills.I would go back
To the Country of the Young,
And see again
The lances of the Shee,As they keep their hosting
With laughing cries
In pale places
Under the moon.