Symbolism, Imagery, Allegory
This is what you've all been waiting for. Ask anyone about The Adventures of Tom Sawyer, and she'll probably say something like, "That's the one with the fence, right?" (Unless you ask us. We'll talk your ear off.) But yes, it's true, The Adventures of Tom Sawyer is "the one with the fence." This isn't any old picket fence, though. It's "thirty yards of board fence nine feet high" (2.1). That's 800 square feet of fence to paint white.
People remember the fence scenario it because it's so clever. Tom tricks a bunch of boy into thinking that work – the thing that he doesn't want to do – is fun, so that he can spend the afternoon goofing off. He even get the boys to pay him for the "privilege" of painting. He turns punishment into pleasure, and pleases Aunt Polly in the process. Everybody dreams of this kind of thing.
Want more? You're in luck. Twain provides his own analysis of the situation. We here at Shmoop will defer to the master:
Tom said to himself that it was not such a hollow world, after all. He had discovered a great law of human action, without knowing it – namely, that in order to make a man or a boy covet a thing, it is only necessary to make the thing difficult to attain. If he had been a great and wise philosopher, like the writer of this book, he would now have comprehended that Work consists of whatever a body is obliged to do, and that Play consists of whatever a body is not obliged to do.
Well, there you go. A little bit of philosophy for you.