Before revision: Upon which happy event, Keats is moved to write his epic poem : "On First Looking into Chapman's Homer (homer being slang for Homing pigeon, as well as the name of the great Greek poet for whom Keats' poem was actually written).
After revision: Upon which happy event, Keats is moved to write his famous sonnet," "On First Looking into Chapman's Homer (homer being slang for Homing pigeon, as well as the name of the great Greek poet for whom Keats' poem was actually written).