What do the piece of bread, the blizzard and the whip symbolize in this novel?
Though Night is a non-fiction writing, Wiesel uses plenty of symbolism and imagery to tell his story. You mention three symbolic elements: bread, blizzard, and whip. Each has meaning beyond the obvious, and each is symbolic of the desensitization of the prisoners in the camp.
Bread in this novel is symbolic of the desensitization which takes place throughout the story. Elie dismisses the first meal he is given in the camps as being less than palatable. Through the course of his time in the prison, Elie learns to see bread as a life-giving force way beyond the actual properties of the substance. It is used as money, for bartering for greater things--including life. It is used as a reason to kill, as we see several times in the train cars. The Bible says in the end times--when things get horribly bad--essentially that a piece of bread will buy a bag of gold. In this horrible place, that has become true. Bread is more important than life.
The blizzard is another picture of desensitization--not so surprising, considering the literal effects of freezing on the body. When they are forced to march from one camp to another in what becomes a blizzard, some of them fall and the rest keep marching over their dead bodies. When a father falls, a son keeps going--hoping the burden of caring for another, even a loved one, can be left behind.
The whip, too, is an object which creates desensitization. After the first few of the twenty-five lashes have been administered, Elie feels no pain. This is a literal lack of sensation, of course, but also a picture of the numbing effects of being treated like animals in the camps.