Analysis of The Radiant Dark

Should I long that dark were fair? Say, O song.
Lacks my love aught that I should long?
Dark the night with breath all flow'rs
And tender broken voice that fills
With ravishment the list'ning hours.
Whis'prings, wooings,
Liquid ripples, and soft ring-dove cooings,
in low-toned rhythm that love's aching stills.

Dark the night, yet is she bright,
For in her dark she brings the mystic star,
Trembling yet strong as is the voice of love
From some unknown afar.
O radiant dark, O darkly foster'd ray,
Thou hast a joy too deep for shallow day.