The poet, John Keats insisted in his letter to Richard Woodhouse (October 27, 1818), has no self, no character, no identity, but is ever ready to assume identity and enter into a role:

To describe how the poetic imagination moves from nonentity to identity, Keats introduces contrasting Shakespearean characters: the innocent Imogen, the evil Iago. Whatever their moral difference, both have equal affective value because “both end in speculation.” The poet is always ready for such role-playing, “continually in for and filling some other Body.” Keats's theatrical metaphor for entering into character might seem to apply broadly to the assumptions about acting in the period. The successful performer, a Sarah Siddons or a John Philip Kemble, is presumably one who can enter convincingly into role and become that character for the duration of the play.