It has been generally supposed that Wordsworth’s theory of poetic language is merely a reaction against, and a criticism of, ‘the Pseudo Classical’ theory of poetic diction. But such a view is partially true. His first impulse was less a revolt against Pseudo-classical diction, “than a desire to find a suitable language for the new territory of human life which he was conquering for poetic treatment”. His aim was to deal in his poetry with rustic and humble life and to advocate simplicity of theme. Moreover, he believed that the poet is essentially a man speaking to men and so he must use such a language as is used by men. The pseudo classicals advocated that the language of poetry is different form the language of prose while Wordsworth believes that there is no essential difference between them. The poet can communicate best in the language which is really used by men. He condemns the artificial language. Thus William Wordsworth prefers the language really used by common men.

Wordsworth’s purpose, as he tells in the Preface was, “to choose incidents and situations from common life”, and quite naturally, he also intended to use, “a selection of language, really used by men”. He was to deal with humble and rustic life and so he should also use the language of the rustics, farmers, shepherds who were to be the subjects of his poetry. The language of these men was to be used but it was to be purified of all that is painful or disgusting, vulgar and coarse in that language. He was to use the language of real men because the aim of a poet is to give pleasure and such language without selection will cause disgust.

The use of such a simple language has a number of advantages. The rustic language in its simplicity is highly emotional and passionate. This is more so the case when these humble people are in a state of emotional excitement. It is charged with the emotions of the human heart. Such a language is the natural language of the passions. It comes from the heart, and thus goes direct to the heart. In other words, through the use of such a language essential truths abut human life and nature can be more easily and clearly communicated. It is more ‘philosophical’ language inasmuch as its use can result in a better and clearer understanding of the basic truths. But in city life emotions are not openly expressed.

Wordsworth was going to write about simple life so he writes in simple language and for this he adds metre. In his opinion, the language of poetry must not be separated from the language of men in real life. Figures, metaphors and similes and other such decorations must not be used unnecessarily. In a state of emotional excitement, men naturally use a metaphorical language to express themselves forcefully. The earliest poets used only such metaphors and images as result naturally from powerful emotions. Later on, poets used a figurative language which was not the result of genuine passion. They merely imitated the manner of the earlier poets, and thus arose the artificial language and diction of Pseudo-classics. A stereotyped and mechanical phraseology thus became current. The poet must avoid the use of such artificial diction both when he speaks in his own person, or through his characters.

Wordsworth's theory of poetic diction is of immense value when considered as a corrective to the artificial, inane, and unnatural phraseology current at the time. But considered in itself it is full of a number of contradictions and suffers from a number of imitations. For one thing, Wordsworth does not state what he means by language. Language is a matter of words, as well as of arrangement of those words. It is the matter of the use of imagery, frequency of its use, and its nature, Wordsworth does not clarify what he exactly means by ‘language’.

Coleridge was the first critic to pounce upon Wordsworth's theory of language and to expose its weaknesses. He pointed out, first, that a language so selected and purified, as Wordsworth suggests, would differ in no way from the language of any other men of commonsense. After such a selection there would be no difference between the rustic language and the language used by men in other walks of life.

Secondly, Wordsworth permits the use of metre, and this implies a particular order and arrangement of words. If metre is to be used, the order of words in poetry is bound to differ from that of prose. It does so differ in the poetry of Wordsworth himself. So Coleridge concludes that there is, and there ought to be, an essential difference between the language of prose and metrical composition.

Thirdly, the use of metre is as artificial as the use of poetic diction, and if one is allowed, it is absurd to forbid the use of the other. Both are equally good sources of poetic pleasure.

Fourthly, Coleridge objected to the use of the word real. He writes:

“Every man’s language varies, according to the extent of his knowledge, the activity of his faculties, and the depth or quickness of his feelings. Every man’s language has, first, its individualities; secondly, the common properties of the class to which he belongs; and thirdly, words and phrases of universal use. For, ‘real’, therefore, we must substitute, ‘ordinary’ or lingua communis.”

Fifthly, Coleridge pointed out that it is not correct that the best parts of our language are derived from Nature. Language is letter-moulded. The best words are abstract nouns and concepts. It the poet wants to use the rustic language, he must think like the rustics whose language is curiously inexpressive. It would be putting the clock back. Instead of progression it would be retrogression.

Wordsworth's theory of language has strong weaknesses, but its significance is also far-reaching. O. Elton concludes his discussion of the subject with the following admirable words:

“Wordsworth, led by his dislike of, ‘glossy and unfeeling diction’ … was led to proclaim that speech as the medium desired; that he guarded this chosen medium not indeed from his own misapplication of it, but … proved its nobility in practice; that he did not clearly say what he meant by, ‘language’, or see the full effect upon the diction by the employment of metre; that he did not rule out other styles … he did not touch on their theoretic basis; and that in many of his actual triumphs, won within that sphere of diction which he does vindicate.”