William Wordsworth says

Poetry is the spontaneous overflow of powerful feelings: it takes its origin from emotion recollected in tranquillity: the emotion is contemplated till, by a species of reaction, the tranquillity gradually disappears, and an emotion, kindred to that which was before the subject of contemplation, is gradually produced, and does itself actually exist in the mind. In this mood successful composition generally begins, and in a mood similar to this it is carried on; but the emotion, of whatever kind, and in whatever degree, from various causes, is qualified by various pleasures, so that in describing any passions whatsoever, which are voluntarily described, the mind will, upon the whole, be in a state of enjoyment. If Nature be thus cautious to preserve in a state of enjoyment a being so employed, the Poet ought to profit by the lesson held forth to him, and ought especially to take care, that, whatever passions he communicates to his Reader, those passions, if his Reader’s mind be sound and vigorous, should always be accompanied with an overbalance of pleasure. Now the music of harmonious metrical language, the sense of difficulty overcome, and the blind association of pleasure which has been previously received from works of rhyme or metre of the same or similar construction, an indistinct perception perpetually renewed of language closely resembling that of real life, and yet, in the circumstance of metre, differing from it so widely—all these imperceptibly make up a complex feeling of delight, which is of the most important use in tempering the painful feeling always found intermingled with powerful descriptions of the deeper passions. This effect is always produced in pathetic and impassioned poetry; while, in lighter compositions, the ease and gracefulness with which the Poet manages his numbers are themselves confessedly a principal source of the gratification of the Reader. All that it is necessary to say, however, upon this subject, may be effected by affirming, what few persons will deny, that, of two descriptions, either of passions, manners, or characters, each of them equally well executed, the one in prose and the other in verse, the verse will be read a hundred times where the prose is read once.