In The Magic Mountain, snow is the perfection that kills: in the section "Snow," in chapter VI, a storm nearly takes Hans Castorp, and it is while lost in it that he reaches the novel's only clear answer, that love, and not reason, is stronger than death.
In the second winter, Hans Castorp buys skis so he can be alone with his own thoughts, and he strays from the beaten paths. Before the storm, he watches the snowflakes on his sleeve and notices that they are "excessively regular," with a precision that seems to him deadly, like the mystery of death itself. Caught by the snowfall, he falls asleep beside a shed and dreams: first of courteous young people on the shore of a gulf, then, inside a temple, of two gray-haired women who tear apart and devour a child.
Between sleep and waking, he rejects the two masters, calls Naphta and Settembrini charlatans, and decides not to grant death any power over his thoughts. But, on his way back, that very same night he no longer quite understands what he thought.
That is why snow is at the center of the book. It is the only place where the answer appears, and it appears outside the sanatorium, to a lone, half-frozen man, coming from a dream and not from a debate. The novel gives the character the sentence that would resolve everything and does not let him keep it.