Joel Elias Spingarn (1875-1939), Creative Criticism and Other Essays (New York: Henry Holt and Company, 1931), pp. 49-50:
The fact that two lines have the same external succession of beats or accents, conform or do not conform to the same “metre,” follow or do not follow some traditional system of versification, tells us no more about their intrinsic quality as poetry than the fact that two men have the same bones or the same lymphatic system tells us about their special qualities as statesmen, as friends, or as men.
What is true of metre is also aesthetically true of language itself. To speak of “learning a language” is to risk the danger of the same confusion, for we do not learn language, we learn how to create it.