The Cambridge History of English and American Literature in 18 Volumes (1907–21).
Volume XI. The Period of the French Revolution.

XI. The Prosody of the Eighteenth Century

§ 13. Cowper

Last of all—for the remarks to be referred to belong, like most of his practice, and, for the same unhappy reason, in the main, to a very late period in his life—we must mention Cowper. His letters, like those of Southey afterwards, show that he might have written consecutively on prosody in a very interesting fashion; but it may be doubted whether he had cleared his mind quite enough on the subject. All know his attack on Pope; or, at least, on the zanies of Pope, with their “mechanic art” and rote-learnt tunes. His prose allusions to the subject are of the same gist, but show the uncleared confusion. The statement that Milton’s “elisions lengthen the line beyond its due limits” may seem to a modern reader sheer nonsense—equivalent to saying that if, in correcting a proof, you cut out a line here and a line there you lengthen the page. But, of course, by “elisions,” he meant the syllables which the arbitrary theory of his time supposed to be elided. Yet he laid down the salutary rule that “without attention to quantity good verse cannot possibly be written”; he declared his faith in “shifting pause and cadence perpetually,” and he knew that, by following this practice (which, it should be remembered, Johnson had denounced as “the methods of the declaimer”), you could make blank verse “susceptible of a much greater diversification of manner than verse in rime”—a point which, with others in reference to “blanks,” occupies most of his letters to Thurlow. He never completed a system to match his practice; but, like this, his theory, such as it was, evidently looked backward to Milton, and forward to the great poets who were boys or not yet born when Cowper seriously began to write.