In Coleridge's Biographia Literaria, he says that it is legitimate to call any composition composed using rhyme and meter a poem. In the text he says, "If a man chooses to call every composition a poem, which is rhyme, or measure, or both, I must leave his opinion uncontroverted." He goes on to repeat this when he says, "the composition will be a poem, merely because it is distinguished from composition in prose by metre, or by rhyme, or by both conjointly." In both of these he asserts that a poem is a composition with rhyme and meter.
