It exists in two versions, with minor differences between them. The original was written by Keats in 1819. He used the title of a 15th century poem by Alain Chartier, though the plots of the two poems are different. The poem is considered an English classic, stereotypical to other of Keats' works. It avoids simplicity of interpretation despite simplicity of structure. At only a short twelve stanzas, of only four lines each, with a simple ABCB rhyme scheme, the poem is nonetheless full of enigmas, and has been the subject of numerous interpretations.