Tom Sawyer Close Reading

"He had had a nice, good, idle time all the while--plenty of company--and the fence had three coats of white of whitewash on it! If he hadn't run out of whitewash, he would have bankrupted every boy in the village.
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 a covet thing, it is only necessary to make it difficult thing 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."

This passage shows Tom's views on human nature. He believes that the only difference between play and work is obligation. This is an important viewpoint because it shows that Tom has figured out a way how to manipulate people. If he can understand the foundation of human emotion, he can make people do the things he wants them to, as he ends up doing later in the book. This key law of human nature is the key to Tom's existence. If he hadn't learned this, he would not be able to go out and explore nature because he would not be done with his chores assigned.
The "fence" in this passage represents a boundary between the town and nature. The fact that he has to coat the fence three times shows that he must stay by the boundary for a long time. This causes a huge temptation for Tom to leave the civil and enter the primal. It is because he wants to venture into nature so badly that he uses the law of human nature that he discovers above to manipulate people in order to get into nature even faster.
The fact that the only thing that stopped Tom from continuing from taking from other was the lack of whitewash shows that he does not know limits. He cares only for himself and his own self-interest, which in most cases is escaping over the fence into the natural world. For Tom, everything is about nature.