Ephemera are things that last only a moment, and the poem captures a fleeting scene along the Yangtze. It moves through glimpses rather than a story: glowing riverbanks, the green of a wood, the smell of something nearly ripe, a lantern's light under a blackened sun. The speaker seems to be watching and absorbing, more than explaining. The reference to "Cold Mountain" gives the setting a quiet, contemplative feel, as if the speaker were looking for peace in nature.
The images are sensual and strange. A sound "rolls naked as a ship" across "dragon-fly wings," blending hearing, sight and touch. In the last stanza the mood settles. There is no wind, a white heron rises, and the sky seems to run deep beneath a rower's boat, so that heaven and water trade places. The feeling is of calm wonder, with a touch of longing, since everything shown is beautiful but passing.