What are the main themes in the novel, Lest Darkness Fall?

Two important themes in the novel are that of the "castaway" and survival. Like Defoe's Robinson Crusoe (1719), in which the main character is shipwrecked on an island far from civilization and must use his ingenuity to survive on his own, Padway is a "castaway" in sixthcentury Italy. Like Crusoe, he must find ways to feed, clothe, and house himself, and he must learn to cope with his strange new environment.