During the winter, how does Dexter reflect upon his summer activities?

During the winters, Dexter skis over the snow-covered Sherry Island Golf Course where, during the summers, he works as a caddie. Though the winter closes on Minnesota like "the white lid of a box," his experiences with the wealthiest members of the community during the summer motivate him in the winter. In the autumn, he has fantasies of grandeur, of impressing Mr. Mortimer Jones, the most prominent citizen in Black Bear, Minnesota, with diving tricks at the golf club's pool or of ordering imagined employees around.
Dexter wants to become like the men on his golf course and uses his observations of them during the summer to imagine what kind of man he wants to be. Though it depresses him to see the golf course—a site of so much activity during the summer—become still and blanketed in white during the winter, that "blank" white space becomes the space where he creates his dreams.