“Dover Beach” offers an early example of an English-language poem written in free verse, meaning that it does not subscribe to a regular, repeating metrical form. Although “free verse” did not arise as a literary term until the twentieth century, it nicely describes the complex rhythms of Arnold’s poem. No two lines in “Dover Beach” have the same exact meter. Instead, the rhythm shifts with the changing cadence of the speaker’s thoughts. The poem opens with an underlying iambic rhythm. The first two lines establish this rhythm, which is then broken in the third line:

     The sea is calm to-night.
     The ride is full, the moon lies fair
     U-pon the straits—on the French coast the light.

Though they differ in number of metrical feet, lines 1 and 2 both consist entirely of iambs. (Recall that an iamb is a foot with one unstressed and one stressed syllable, like “to-day”). The first two feet of line 3 are also iambs. But then, after the long dash, the iambic rhythm falters. Arnold gives us one pyrrhic foot (i.e., two unstressed syllables, “on the”) and one spondee (i.e., two stressed syllables, “French coast”), before returning with another iamb (“the light”). With this interruption, any sense of metrical regularity falls apart.

Arnold uses free verse to underscore the speaker’s sense that the world is uncertain and unpredictable. Over the course of the poem, the speaker grows increasingly preoccupied by his own dark thoughts about the human condition. In a world where the influence of faith is receding like the ebbing tide, and where “ignorant armies clash by night” (line 37), there can be no real sense of stability. Arnold reflects the underlying instability of the world in his unstable use of meter. The only example of perfectly regular meter repeated across two lines comes in the fourth and final stanza. Here, the speaker declares that the world:

     Hath real-ly nei-ther joy, nor love, nor light,
     Nor cer-ti-tude, nor peace, nor help for pain.
(lines 33–34)

Here, Arnold uses strict iambic pentameter to describe the world’s many imperfections—including the lack of “certitude.” In a clever form of paradox, Arnold suggests that the only certainty is, perhaps, that there is no certainty.