Eliezer notices that mrs. schächter doesn't seem affected by the optimism the other prisoners on the train feel when they hear what the two men who fetched water tell them. how does this contrast to develop one of the key themes in night?

This contrast revealed that Mrs. Schachter becomes an impediment to the prisoners' attempts to remain hopeful.

Explanation:

While they were going in the car train Mrs. Schachter was not as positive and hopeful as the others on board, since she had seen in her vision flames of fire coming from a crematory and even when some people tough she had lost her mind other believed her, and later on their way they tragically saw that her words were not caused by madness, they were prophetic words or the horrors to live.

i think the life is invaluable.

you can also say immeasurable.

where exactly is the sentence