In "Dover Beach," the speaker tells us that history often repeats itself and that all human beings share a universal human experience. Additionally, the language of sadness is recognizable no matter what era one lives in.
The second stanza underlines the "eternal note of sadness" in the first stanza. The speaker tells us that this despondency is universal throughout time. Even Sophocles experienced this same feeling of sadness when he once listened to the waves of the Aegean Sea. The ebb and flow of the waves bring to "mind the turbid ebb and flow / Of human misery." Misery is not only universal in the human experience, but it also never ceases to torment each succeeding generation. So, misery is like the ebb and flow of the waves; it never stops plaguing mankind.
Indeed, the speaker contends that the world has "really neither joy, nor love, nor light, / Nor certitude, nor peace, nor help for pain." He argues that the world is a dark place, where "ignorant armies clash by night" and life consists of a never-ending "struggle and flight" in the quest for survival.