What does the way the other jews treat Madame Schacter reveal about human nature?
Madame Schachter has been traumatized when she is first mentioned in Night by unintended separation from her husband and sons, transported by mistake in a different train than she and her youngest son. She is distressed to the point of hysteria even before the terrors of transportation and the concentration camp become her present reality.
The other Jews at first do their best to care for her, to provide comfort and reassurance to the poor, troubled woman. They physically care for her needs with "a damp rag on her forehead." Their words of hope mean nothing to her, however, and the efforts become reasoning "with her, more to calm ourselves, to catch our breath, than to soothe her." The group personality has to preserve its own sanity, even when it can't help Madame.
When her hysterical outbursts continue, she is forcibly bound and gagged - the only recourse of the group that needed to contain its terror by controlling whatever it could of the forces that heightened the awareness of the awful situation in which they were trapped. Self-preservation is always the final and most basic instinct of human nature.