One of the things that I try to stress in my classes and my book is how much that what seems natural to us economically is actually cultural and historical. When Jefferson, for example, argued that in embracing industry the young United States will be making its citizens less independent, he is really not wrong. The yeoman agriculturalist might have been a Jeffersonian ideal more than a reality, but there is more than a kernel of truth to the notion that those who produce their own food are independent of other in a way that those who do not do so simply are not. We don't feel dependent on employers, banks, agricultural conglomerates and so on, but without them most of us would starve to death pretty quickly. The larger implication is that the arrangement that you're "used to" might not be a good device for achieving its stated goal or the the idea that seems "obvious" might actually be wrong.
In this vein, one of the most significant points that I try to make is that the idea of working for money is something that had to be invented. If everyone else is living in some other sort of economy--one governed by barter, say, or feudal or familial relationships--it wouldn't do you much good to be the only person in town with a little cash, because no one would have any use for your currency. The NPR podcast Planet Money has produced an episode that echoes this point by asking, "Who had the first job?"
The answer is a bit underwhelming; even the expert they're interviewing suggests that there's more work to be done to tackle the question seriously. But the reporter Adam Davidson, who is working on a new book about (as I understand it) the ways in which the economy of today might not match up with the stories we tell about it, does a good job in explaining the significance of the question.