At the start of Chapter 3, Eliezer and the others have just arrived at Birkenau after their long and dreadful journey on the train. They are immediately forced to leave all their belongings, along with any hopeful illusions, behind on the train. After the men and women are separated and they are evaluated, Elie and his father are brought to their barracks. When they get there, they are forced to remove their clothing, keeping only their belts and shoes.
Elie does not explicitly tell the reader what he is thinking in these moments when he loses his remaining belongings. He seems more concerned with staying with his father than with his few possessions. The chaos and the confusion of the whole situation seem to overwhelm him and everybody else and they appear to abandon their possessions with very little thought about it. As he writes, "our senses were numbed, everything was fading into a fog. We no longer clung to anything."
This is the beginning of the process in which Elie finds himself changing from a caring young man to a detached survivor. For instance, he is inwardly shocked that he does not react when his father is struck by another prisoner right in front of him. As his ordeal at Auschwitz-Birkenau continues, Elie continues to experience the erosion of his humanity.