“[I]f Poetry comes not as naturally as the Leaves to a tree it had better not come at all,” proposed John Keats in an 1818 letter, at the age of 22. This could be called romantic in sentiment, lowercase r, meaning fanciful, impractical, unachievably ambitious. But Keats’s axiom could also be taken as a one-sentence distillation of British Romanticism—with its all-or-nothing stance on the spontaneity of the highest art, its conviction of the sympathetic connections between nature’s organic growth and human creativity, and its passion for individual imagination as an originating force. This period is generally mapped from the first political and poetic tremors of the 1780s to the 1832 Reform Act. No major period in English-language literary history is shorter than that half-century of the Romantic era, but few other eras have ever proved as consequential. Romanticism was nothing short of a revolution in how poets understood their art, its provenance, and its powers: ever since, English-language poets have furthered that revolution or formulated reactions against it.

In Britain, Romanticism was not a single unified movement, consolidated around any one person, place, moment, or manifesto, and the various schools, styles, and stances we now label capital-R Romantic would resist being lumped into one clear category. Yet all of Romanticism’s products exploded out of the same set of contexts: some were a century in the making; others were overnight upheavals. Ushered in by revolutions in the United States (1776) and France (1789), the Romantic period coincides with the societal transformations of the Industrial Revolution, the rise of liberal movements and the state’s counterrevolutionary measures, and the voicing of radical ideas—Parliamentary reform, expanded suffrage, abolitionism, atheism—in pamphlets and public demonstrations. Though Britain avoided an actual revolution, political tensions sporadically broke out into traumatizing violence, as in the Peterloo massacre of 1819, in which state cavalry killed at least 10 peaceful demonstrators and wounded hundreds more.

Emboldened by the era’s revolutionary spirit, Romantic poets invented new literary forms to match. Romantic poetry can argue radical ideas explicitly and vehemently (as in Percy Bysshe Shelley’s “England in 1819,” a sonnet in protest of Peterloo) or allegorically and ambivalently (as in William Blake’s “The Tyger,” from Songs of Innocence and of Experience). To quote from William Wordsworth’s preface to Lyrical Ballads, the groundbreaking collection he wrote with fellow poet-critic Samuel Taylor Coleridge, Romantic poets could “choose incidents and situations from common life” as its subjects, describing them not in polished or high-flown diction but instead in everyday speech, “a selection of language really used by men.” Romanticism can do justice to the disadvantaged, to those marginalized or forgotten by an increasingly urban and commercial culture—rural workers, children, the poor, the elderly, or the disabled—or it can testify to individuality simply by foregrounding the poet’s own subjectivity at its most idiosyncratic or experimental.

Alongside prevailing political and social ideas, Romantic poets put into practice new aesthetic theories, cobbled from British and German philosophy, which opposed the neoclassicism and rigid decorum of 18th-century poetry. To borrow the central dichotomy of critic M.H. Abrams’s influential book The Mirror and the Lamp (1953), Romantic poets broke from the past by no longer producing artistic works that merely mirrored or reflected nature faithfully; instead, they fashioned poems that served as lamps illuminating truths through self-expression, casting the poets’ subjective, even impressionistic, experiences onto the world. From philosophers such as Edmund Burke and Immanuel Kant, the Romantics inherited a distinction between two aesthetic categories, the beautiful and the sublime—in which beautiful suggests smallness, clarity, and painless pleasure, and sublime suggests boundlessness, obscurity, and imagination-stretching grandeur. From the German critic A.W. Schlegel, Coleridge developed his ideal of “organic form,” the unity found in artworks whose parts are interdependent and integral to the whole—grown, like a natural organism, according to innate processes, not externally mandated formulas.

The most self-conscious and self-critical British poets to date, the Romantics justified their poetic experimentations in a variety of prose genres (prefaces, reviews, essays, diaries, letters, works of autobiography or philosophy) or else inside the poetry itself. But they never wrote only for other poets and critics: the Romantics competed in a burgeoning literary marketplace that made room for the revival of English and Scottish ballads (narrative folk songs, transcribed and disseminated in print), the recovery of medieval romances (one etymological root of Romantic), and prose fiction ranging from the psychological extremes of the gothic novel to the wit of Jane Austen’s social realism. Romantic poets looked curiously backward—to Greek mythology, friezes, and urns or to a distinctly British cultural past of medieval ruins and tales of knights and elves—to look speculatively forward. Perhaps no pre-Romantic author inspired the Romantics more than William Shakespeare, who exemplified what Keats termed “Negative Capability, that is when a man is capable of being in uncertainties, Mysteries, doubts, without any irritable reaching after fact & reason.” For Keats, “a great poet” such as Shakespeare opened his imagination to all possibilities, limited neither by an insistent search for truth nor by his own egocentric gravity: “the sense of Beauty overcomes every other consideration, or rather obliterates all consideration.”

Drawing on unrestrained imagination and a variegated cultural landscape, a Romantic-era poem could be trivial or fantastic, succinctly songlike or digressively meandering, a searching fragment or a precisely bounded sonnet or ode, as comic as Lord Byron’s mock epic Don Juan or as cosmologically subversive as Blake’s The Marriage of Heaven and Hell. If any single innovation has emerged as Romanticism’s foremost legacy, it is the dominance among poetic genres of the lyric poem, spoken in first-person (the lyric I) often identified with the poet, caught between passion and reason, finding correspondences in natural surroundings for the introspective workings of heart and mind. If any collection cemented that legacy, it would be Wordsworth and Coleridge’s landmark collection Lyrical Ballads, first published anonymously in 1798. The collection provokes with its title alone, inverting hierarchies, hybridizing the exalted outbursts of lyric poetry with the folk narratives of ballads. In a retrospective preface added for the 1800 second edition and expanded in later editions, Wordsworth set out his polemical program for a poetry grounded in feeling, supplying Romanticism with some of its most resonant and lasting phrases: “all good poetry is the spontaneous overflow of powerful feelings”; “it takes its origin from emotion recollected in tranquillity.”

The following poems, poets, articles, poem guides, and recordings offer introductory samples of the Romantic era. Included are the monumental Romantic poets often nicknamed “the Big Six”—the older generation of Blake, Wordsworth, and Coleridge and the so-called Young Romantics—Byron, Shelley, and Keats. Indispensable women poets such as Charlotte Smith, Mary Robinson, and Felicia Dorothea Hemans; the Scottish poet and lyricist Robert Burns; and the farm laborer–poet John Clare are also represented. But even this collection is only a beginning: no introduction to Romanticism can encompass the entire period in all its variety and restless experimentation.