This is actually a re-post from 2013, but it's a perennial favourite - and seasonally appropriate to boot!
Seasons greetings, everyone!
I've noted previously that Ray Bradbury wrote very few Christmas-themed stories, but one of his best-known is "The Gift". It was first published in Esquire magazine in 1952. The artwork above (click to embiggen) is by Ren Wickes, and in the child's face beautifully captures the good old "sense of wonder" people used to talk about in science fiction stories.
To find out why the child is so astonished, read "The Gift" here.