While her husband Percy encouraged her writing, the extent of Percy's contribution to the novel is unknown and has been argued over by readers and critics.Seymour, 195–96. Mary Shelley wrote, "I certainly did not owe the suggestion of one incident, nor scarcely of one train of feeling, to my husband, and yet but for his incitement, it would never have taken the form in which it was presented to the world." She wrote that the preface to the first edition was Percy's work "as far as I can recollect." There are differences in the 1818, 1823 and 1831 editions, which have been attributed to Percy's editing. James Rieger concluded Percy's "assistance at every point in the book's manufacture was so extensive that one hardly knows whether to regard him as editor or minor collaborator", while Anne K. Mellor later argued Percy only "made many technical corrections and several times clarified the narrative and thematic continuity of the text." Charles E. Robinson, editor of a facsimile edition of the Frankenstein manuscripts, concluded that Percy's contributions to the book "were no more than what most publishers' editors have provided new (or old) authors or, in fact, what colleagues have provided to each other after reading each other's works in progress."Robinson 1996, part 1, p. lxvii, quoted in Jones 1998.
