Samuel Taylor Coleridge wrote “Frost at Midnight” in five stanzas of blank verse. Blank verse consists of unrhymed iambic pentameter (or lines of five metrical feet that follow an unstressed/stressed syllable pattern) and is one of the most common metrical forms in English. John Milton’s Paradise Lost, which is a prominent influence among Romantic writers, is written in blank verse. Romantic authors tended to prefer the form due to its relative freedom of expression compared to stricter historical forms that incorporated rhyme schemes. The poem’s focus on Coleridge’s internal life makes it a lyric work.

Though Coleridge’s collaborator William Wordsworth places naturalistic, spoken language among the tenets of Romantic poetry, Coleridge writes in a variety of registers. “Frost at Midnight” moves between heightened language and contemporary vernacular. Coleridge’s use of antiquated terms like “sleepest” (Line 45) or “so shalt thou see” (Line 59) lends the poem a formal, authoritative tone. This heightened language—and, in particular, Coleridge’s use of the antiquated, informal, second-person “thou”—peaks in the fourth stanza as he discusses his child’s natural education (See: Themes). The language in the fourth stanza, in this way, mirrors the formal, imperative tone of the Christian Bible.