The first stanza of Matthew Arnold's "Dover Beach" describes the scenery in terms of three senses: sight, hearing, and smell. The first few lines describe how the English Channel looks in the moonlight. They describe the white cliffs of Dover glimmering in the moonlight. As the French coast is described as only intermittently visible, there are probably some clouds, making the light appear and disappear.
As the poet addresses his beloved and asks her to come to the window, the sensual imagery briefly shifts to smell, and the air coming in through the open window is described as "sweet."
The poem then shifts back to the sense of sight in the mention of a "long line" of spray where the edge of the sea meets the sand. Next, belying the initial description of the sea as calm, the narrator describes the sound of the waves flinging pebbles on the shore, and then the "grating roar" as the water recedes. The final lines of the stanza link the sound of the waves, with their slow cadence, to a metaphorical "eternal note of sadness."
The sea is calm tonight.The tide is full, the moon lies fairUpon the straits; on the French coast the lightGleams and is gone; the cliffs of England stand,Glimmering and vast, out in the tranquil bay.
Come to the window, sweet is the night-air!
Listen! you hear the grating roarOf pebbles which the waves draw back, and fling,At their return, up the high strand,Begin, and cease, and then again begin,With tremulous cadence slow, and bringThe eternal note of sadness in.