In literature, and especially in poetry, decorum is consistency with the canons of propriety; a matter of behaviour on the part of the poet in his poem, and therefore what is proper and becoming in the relationship between form and substance. Action, character, thought and language all need to be appropriate to each other. At its simplest, the grand and important theme (for instance that of Paradise Lost) is treated in a dignified and noble style; the humble or trivial (for example, Skelton’s The Tunning of Elynour Rumming) in a lower manner.
Decorum was of considerable importance to Classical authors. Aristotle deals with it in Poetics; Cicero in De Oratore; Horace in Ars Poetica. What they said had wide influence during and after the Renaissance, though there were many who did not subscribe to their dictates.
Many Elizabethan plays, for example, show an awareness of certain rules of decorum. An obvious instance is Much Ado About Nothing (c. 1598–9). It being a comedy of manners (q.v.), all the comic passages, especially the badinage between Beatrice and Benedick, are written in colloquial dramatic prose; the romantic episodes and themes are always rendered in verse. As soon as Benedick and Beatrice realize they are in love, the emotional temperature rises and they speak in verse.
Decorum became of great importance towards the end of the 17th c. and during the 18th when Classical rules and tenets were revered. The use of correct language was of particular interest. For instance, Samuel Johnson observed that the words ‘cow-keeper’ and ‘hog-herd’ might not be used in our language; but he added that there were no finer words in the Greek language. Though the subject matter of 18th c. writers was often what they thought of as ‘low’, if not vulgar, they managed to dress it in appropriate language. Pope combines elegance, wit and grace with an almost brutal forcefulness and succeeds in writing of the crude, the corrupt and the repulsive without offending.
Wordsworth and Coleridge found the doctrines of Neoclassicism too restrictive; hence Wordsworth’s attempt, as expressed in the Preface to Lyrical Ballads, to rebel against ‘false refinement’ and ‘poetic diction’.
Since then writers have always considered matters of literary decorum, though in a more flexible way. Dickens is a good example of a writer who adjusts his style to the needs of the moment. Fundamentally, most people have an awareness of the need to adjust their language to the occasion, whether they are writing or speaking.