When Holden and other boys come out of the dining room, they see the pristine snow which has fallen.
. . . we all started throwing snowballs and horsing around all over the place. It was very childish, but everybody was really enjoying themselves. (Chapter 5)
Holden decides to join a friend named Mal Brossard on a trip into Hagerstown to have a hamburger and watch a movie. Because he has asked Mal if Ackley can come along, he must wait while Ackley gets ready. As he waits, Holden opens the window and packs a snowball. This time, however, Holden does not throw his snowball because when he gets ready to throw it, he notices how each target he selects looks "so nice and white" that he does not want to change anything by tossing a snowball on it.
Holden refrains from throwing the snowball out the window because it looks perfect; also, the parked car and fire hydrant seem pristine, and he does not wish to mar them by striking them with the snowball. Holden's name itself suggests his problem: He wants to "hold on" to things and people in their pristine states. This attitude extends to his desire to catch children and prevent their falling into the corrupt adult world and why he tells his sister he wants to be "a catcher in the rye," holding back innocent children.