Catholic Orphange
Felix has survived the horrific violence of the Holocaust and World War II, more generally because he was safe at the Catholic orphanage. If he were not there, he would have met the same fate many Jewish children faced: death. Despite this, Felix unexpectedly left the orphanage, thereby putting himself in danger.
Felix
On more than one occasion, Felix decides to go near Nazi soldiers. He does so despite seeing the terrible things the Nazis inflicted on people (mainly Jewish people). All Jewish people, matter their age, make a point to avoid Nazis, but Felix unexpectedly does not, which causes him to die on several occasions nearly. This irony reflects Felix's naivete and his young age.
Fire
On Felix's journey to the city, he comes across a burning house. Most people wouldn't enter a home when it is on fire, but Felix did because he felt that someone could be inside, and he wanted to save them, which shows how big of a heart he has.
Books
Books are repositories of knowledge that are very valuable to people worldwide. However, the Nazis decided to burn books (as Felix saw firsthand in his orphanage) despite their value, reinforcing how nonsensical the Nazis were.
