It’s a commonplace that there are some things money can’t buy. [Georg] Simmel had a more striking insight: Having money can actually be more satisfying than having the things money can buy. That’s because […] money has a “surplus value.” A person with money enjoys the added satisfaction of having a choice of things to buy: “The value of a given amount of money is equal to the value of any object for which it might be exchanged plus the value of free choice between innumerable other objects.”