It is said to have been a boast of Swift, or some of his friends, “that he had hardly a metaphor in all his works.” This, if true, was but a foolish boast. […] It is not easy to conceive why a man should think his style improved by the entire absence, were such a thing possible, of Metaphor. There is, to be sure, a vulgar idea, that a style not metaphorical is necessarily a plain style. In one sense of the word this is true, or rather this is a truism. If, however, by the term “plain,” is to be understood a style more intelligible than other styles, the assertion is unfounded. There can be no doubt, that men ambitious of metaphorical expression, are very liable to fail in their attempt to express themselves metaphorically, and thus darken and confuse their language. But this is not the fault of metaphor. It is the fault of the writer. That a happily written figurative style is not less easy to be comprehended than any other, it needs only a consideration of the nature of Metaphor to show. It is less easy of attainment than a plainer method; but when attained, just as obvious to the comprehension of the reader. A Metaphor may be defined to be the appellation of something by the name of some other thing, to which it has some similitude, or with which it has some quality in common. Dr. Johnson well describes it as “a simile in one word.” Now what has been the original reason of authors, whether of prose or poetry, adopting this expedient? Surely not the desire of being unintelligible! If we only ask the question why are metaphors made use of, the plain answer is this — to render more striking some unusual or abstract expression, by joining to it another idea which is less common, or less abstract, to illustrate the first. Thus we say “striking effect,” adding to the abstract general idea of effect, the visible idea of a blow; and this we do to give additional force and meaning to the phrase, and for no other reason. What is the reason of poets being so wedded to the employment of metaphors? Not for the sake of being obscure — that they can be easily enough, God knows, without metaphors; but for the sake of that force and intensity of meaning, which is the pith and marrow of poetry, and which is best attainable by the employment, where it is possible, of vivid and distinct imagery. It is for this reason that an original metaphor is better than one that is not original. It attracts the attention more strongly, and stamps the impression more forcibly upon the mind. Trite metaphors in time cease to be metaphors; even as Addison’s lady was described by him, to have become of no sex after a few anniversaries of the honey-moon. We employ them without knowing that we do so; and this accounts for the boast of Swift or his friends, with his books before them and their eyes open. It is perhaps almost impossible to construct a language which shall be divested of metaphor.
(Thomas Doubleday, “On the Use of Metaphors,” Blackwood’s Magazine, Vol. XVIII, 1825, pp. 719–720).