You'll notice suffering from page one of The Book Thief. Cold, hunger, emotional and physical abuse, guilt, the horror of the battlefield – all these play heavily into the suffering of the characters. Set primarily in Nazi Germany during the Holocaust, suffering is the rule, not the exception. The novel doesn't enter the concentration camps and focus on the immense sufferings occurring there. Instead, these camps are a dark shadow coloring everything in horror and fear. Suffering and guilt over the loss of loved ones is also a major focus in The Book Thief.
Learning to comfort and aid those who are suffering is a big part of Liesel's development as a person.
The novel argues that trying to ease suffering is the noblest of causes.