Why does the man have trouble lighting the matches?

The man has trouble lighting the fire because he has no feeling in his fingers. They've gone numb with the cold. 

The bare fingers were quickly numb again. Next, he brought out his pack of matches. But the awful cold had already driven the life out of his fingers. In his effort to separate one match from the others, the whole pack fell in the snow. He tried to pick it out of the snow, but failed. The dead fingers could neither touch nor hold.