How do Madame Schaechter's screams act as forshadowing?

In this section, however, the silence (and generally quiet tone of the novel) is violently shattered by the hysterical screaming of Madame Schaechter. Her violent shrieks are what finally destroy the trusting naivete of the Jews and begin to make them afraid of what is to happen to them: "The heat, the thirst, the pestilential stench, the suffocating lack of air‹these were as nothing compared with these screams which tore us to shreds. A few days more and we should all have started to scream too." Her screaming symbolizes the hellish world of insanity that they have entered into, as opposed to the world of calm, quiet, and security that they have just left behind.

Though Madame Schaechter is a fifty-year-old woman and obviously unwell, she is beaten repeatedly about the head by young men trying to silence her. And her little boy says nothing: "They struck her several times on the head‹blows that might have killed her. Her little boy clung to her; he did not cry out; he did not say a word. He was not even weeping now." The people in the wagon treat her cruelly and inhumanely, as they undoubtedly would not have done under normal circumstances, but Wiesel does not condemn them for their brutal actions. Instead, his tone in this passage is very sad, full of regret and guilt. Since Madame Schaechter's hysterical shrieks was unnerving everyone in the car, he recognizes that it was necessary for their collective survival that she be silenced. At the same time, however, he seems to mourn the fact that such cruel behavior was necessary and that everyone, including the woman's own son, condoned such violent and vicious behavior. In this nightmare world that the Nazis have created for the Jews, survival is the only concern, and human emotions and affective ties become irrelevant.