 The letter Rico receives from Dubois, partly responsible for Rico "crossing the hump" with his training, is shown as a turning point in his development.The classroom scenes embedded in the story serve to explain Rico's adventures, and highlight his reactions to events around.A notable example is the execution Rico is forced to witness after a deserter from his unit murders a young girl; Rico is uncertain of his own reaction until he remembers a lecture by Dubois in which the latter argues that "moral sense" derives entirely from the will to survive.