Scholars have identified several possible origins and antecedents for the chapter, and these have been added to by Christopher Tolkien's exploration of the literary history of his father's work on it over the years. Birns writes that the "Scouring" has an ancient pedigree, echoing Homer's "Odyssey" when after long years away Odysseus returns to his home island of Ithaca to scour it of Penelope's worthless suitors. Robert Plank echoes the comparison with the "Odyssey", adding that Tolkien could have chosen as a pattern any number of other returning heroes. This theme, of a last obstacle to the heroic homecoming, was paradoxically both long-planned (certainly back to the time of writing of the Lothlorien chapter) and, in the person of Saruman-as-Sharkey, "a very late entry". David Greenman both likens the hobbits' scouring of the Shire to Odysseus's return, and contrasts it to Tuor's Aeneas-like escape from a wrecked kingdom as told in "The Fall of Gondolin".