Most theories of interpretation and editing depend on a concept of single authorship. But literary works can and frequently do have multiple authors, sometimes with divided and even conflicting intentions among them.Stillinger explores multiple authorship in the case of Keats and his helpers who assisted in the creation of Isabella; John Stuart Mill and his wife in the writing of Mill's Autobiography; the author revising earlier versions of himself, as with Wordsworth in The Prelude; and the author interacting collaboratively with sources and influences (Coleridge in Biographia Literaria).