It is important that "a set of things" has been changed, and at the end of the story the heroes carry a completely different "things" with them.
The main character of the book is Lieutenant Jim Cross, a man who falls in love with a girl who does not return his feelings. Jim suffers greatly and can do nothing but dreaming about close relations with this girl. His negligence of duties costs life one of his soldiers, and after this terrible event, he puts an end to his false dreams, and rethink most of his values and views. It was really difficult to him to change his worldview but he was strong enough to cope with emotional burden, and re-sort his "things". The main idea of the text is that wartime has a great impact on feelings and views of people. To some extent, this very moment caused the awakening of many characters in the story. For instance, Jim Cross sees the truth of life only when the soldier dies because of his negligence. Obrien depicts that fear applied to love leads to individual degradation. Tolerance protects that diversity and demands respect. Jim Cross is a person who fights with his own imperfection changing his personal views after Ted Lavender's death.