The first thirteen lines of Dover Beach are quite literal. Up to this point, the speaker has described a landscape/seascape. With his lover, looking out across the sea to the coast of France, the speaker comments upon the tranquility of scene. That tranquility is interrupted only by the waves washing back and forth over the pebbles:
Listen! you hear the grating roar
Of pebbles which the waves draw back, and fling, (9-10)
In the fourteenth line, this literal sound is given an emotion, an "eternal note of sadness." This sound then becomes a symbol linking past and present human suffering. In the second stanza, there is a reference to the past. In Sophocles' Antigone, human sorrow is compared to the sound of the waves. In the third stanza, the speaker moves back to the present. The "Sea of Faith" (Christianity) is receding (like the waves) leaving behind the absence of spiritual unity, therefore a world with no unifying hope. In this "darkling plain," the speaker is left with only one consolation: the love of his companion.
These images of sorrow and receding hopes are all set up by the literal description of the sea's ebb and flow.