How does Peter Hoeg use imagery in Smilla's Sense of Snow?

Imagery:

“Do you know what the mathematical expression is for longing? ... The negative numbers. The formalization of the feeling that you are missing something.”

“There's a look of mischief in his eyes. 'Smilla. Why is it that such an elegant and petite girl like you has such a rough voice.'
I'm sorry,' I say, 'if I give you the impression that it is only my mouth that's rough. I do my best to be rough all over.”