I think that Boyne is able to use the mental picture to convey much about the condition of prejudice and discrimination in which Bruno finds himself, but also towards that which he pledges to overcome. The concept of the fence, itself, is one such image. Bruno is repeatedly told about the fence and how he must stay away from it. Yet, by going to the end of it and finding Shmuel, Bruno has been able to appropriate an image of discrimination into one of friendship. At the signt of the two trains, Boyne uses another image to bring out the condition of racism and discrimination that exists in Nazi Germany. Bruno notes how there is a fundamental difference in both trains. The train he is traveling on is radically different than the train that others are boarding with facial expressions of sadness and despair accompanying them. This is another image to bring out how there is a difference that Bruno perceives to bring out the discrimination and racism that exists in his world. The "pajamas" themselves become another image that Bruno appropriates to mean something other than what it does. The uniform that people like Shmuel must wear is the ultimate identification of the discrimination and brutal racism inflicted by the Nazis. Bruno sees them as "pajamas," something that he himself dons at the end of the novel, leading to its climax. In this, Bruno has himself take the objects of racism and discrimination and made them something of solidarity and strength with his friend. These images are what Boyne employs to bring out the condition that surrounds Nazi Germany and the people in it.