The speaker looks back on a childhood spent beside a misty marsh, where he was lonely and, in his imagination, visited every night by pale maidens. Each seems to be tied to a particular flower, with her own face and voice, and each comes to his window with the mist to talk with him until the stars begin to fade. Then she goes back, heavy with dew, to the place she came from.
That place is described in the last stanza as somewhere before things take shape, where bird and flower are "one and the same." From this the speaker claims a kind of secret knowledge: he understands why a flower has its scent and a bird its song. The tone shifts from dreamy and hushed to quietly confident, even a little defensive in the closing lines, as he insists his solitary listening was not wasted. The mood is wistful, mysterious and gently proud, suggesting that loneliness taught him to hear something others miss.