The speaker watches rushes nodding beside a river as wind moves over the water, and he imagines they know many secrets. They seem as old and wise as fairies from before the hills were made, bowing gravely to everyone who passes. The mood is quiet and a little dreamy, full of longing.
If the rushes would share what they know, he could find a hidden path to a rath — an old fairy fort — at dawn or in the dim moonlight. There he hopes to meet a fairy-girl from Leinster and join her in a long dance, heart beating with hers, feet moving in rhythm. The whole feeling is wistful: the speaker is caught between the ordinary riverbank and a beautiful, magical Ireland just out of reach.