Wordsworth was indebted to prevailing critical ideas in the later eighteenth century about the importance of feeling, of emotion, in art. Wordsworth's famous dictum; 'poetry is the spontaneous overflow of powerful feelings … recollected in tranquillity' is very much in this tradition. Broadly speaking, these ideas were in reaction to the cult of reason that characterized the earlier part of the century and the preceding one. (As a cautionary note, we should always be aware, though, that as with any broad generalization, this is something of an oversimplification.) Previously the stress was on art as being artifice, a re-creation of the outer world in an elegant balanced style, formal, organized. Now there was a shift to the idea of art as being natural, springing from the deeps of creativity and imagination of the artist in a freer manner, unconstrained by rules and regulations - although of course in practice it remained very much ordered. We can see how the notion of order was certainly not altogether abandoned by Wordsworth; emotion is vital for poetry, but it is emotion recollected in tranquillity; he does not lose himself completely in the wildness of his emotions.
In the eighteenth-century there was a growing importance of the lyric form, the type of poetry devoted to conveying emotion which had previously been regarded as fairly minor, as opposed to epic or dramatic poetry. The subjective element in art, the influence of the writer or artist’s feelings upon his material, was increasingly encouraged. The ultimate development of this subjectivism can be seen in Wordsworth's most lengthy work The Prelude, an epic of the self.
The shift in ideas about art and literature in the eighteenth century can also be discerned in important other ways. Throughout the century there was a growing taste for writing about nature - rather than just writing in a witty, urbane manner about the ways and foibles of society, as before. This vogue for nature poetry was demonstrated in enormous popularity of James Thomson’s The Seasons. But this was more than just faithful reflection of nature: there was a vital stress on the emotions and passions of the artist inspired by the grandeur of nature. This sense of awe and wonder ignited by the glories, wonders, and also terrors of nature was known as the cult of the sublime, and was generally inspired by the wonders of Alpine scenery, a fashionable travel destination at this time. But there were also nature scenes closer to home, more earthy scenes, laid among English rural folk, for example Oliver Goldsmith’s The Deserted Village. The poor rural classes were already within the purview of writers and artists before Wordsworth began his poetic career, so his declaration in the Preface to the Lyrical Ballads that the rural poor were fit subjects for poetry was rather less revolutionary than is sometimes supposed.
It was the increasing stress in the eighteenth century on the importance of emotion in art, then, that greatly influenced Wordsworth. This championing of feeling in the eighteenth century resolved into the cult of the sublime in poetry, and the cult of sensibility in the increasingly popular prose form known as the novel, where the protagonists’s feelings were all-important, and later memorably satirized by the likes of Jane Austen.