And so to jerf's point, somebody starving places high value on getting one orange, or two. But by the time he's got a pile of a billion oranges, he's really not

And so to jerf's point, somebody starving places high value on getting one orange, or two. But by the time he's got a pile of a billion oranges, he's really not interested in getting any more. Looking at it the other way around, if you give Bill Gates a check for $1,000, he won't notice it. If you gave that same check to a homeless person, or to an impoverished would-be entrepreneur in India, it may change his life. but [money] isn't really what economics is about. David Friedman, son of the famous Milton, wrote: Economists are often accused of believing that everything – health, happiness, life itself – can be measured in money. What we actually believe is even odder. We believe that everything can be measured in anything. To answer the obvious follow-up: Economics is the study of choices: what makes a person choose Option A rather than Option B. So the core concept in economic is opportunity cost.