Money is like Gasoline
Inc. Magazine's article about Tim O'Reilly is very good read and filled with analogies. I like this one the most (nota bene he is very very rich):
"Money is like gasoline during a road trip," he says. "You don't want to run out of gas on your trip, but you're not doing a tour of gas stations. You have to pay attention to money, but it shouldn't be about the money."
