At the end of the first decade of the previous century, the American anthropologist, William H. Furness III, published a book called Island of Stone Money. It was about the monetary system and economy of Yap, a remote island in the Pacific. The people of that island used huge circular stones with holes in them as money. This kind of money was called "fei."

Some fei were 13 feet tall; others, just a foot. All were hard to move from place to place. Also, the people of the island had everything they needed: a few domesticated pigs, fish, coconuts, a small number of vegetables. There was, it appeared, no real need to buy or even barter these few things. They could be had for free. But to William H. Furness III's surprise, they had this sophisticated monetary system of stones. To make matters stranger to his American eyes and sensibilities, the stones were rarely moved around. When a deal was struck with a stone, it usually was not exchanged. It stayed in the buyer's yard, and its new owner only needed to know that the buyer knew it was his.

Here is where Jeff Bezos comes into the picture of this remote island.

Much of his wealth—which caused a lot of excitement yesterday when he reached an estimated worth of $92 billion after earnings expectations spurred Amazon stock to jump—can never be realized or seen. And in this way it is much like the feis the people of Yap use but have never ever seen. They have only heard about these feis. Indeed, one massive stone was said to have fallen into the ocean while being transported by boat from another island. Though it was at the bottom of the ocean (as the boatmen claimed), it had not lost its one bit of its massive value. You could still make deals with it. This stone money nobody had ever seen and would never see.

Bezos overtook Bill Gates in worth for a moment, but by last night, the earning expectations fell short and Bezos lost $6 billion. No one saw that money. We have only heard about it from reporters. We trust our reporters the like the Yep people trusted those boatmen.

For more about this Yap business, read the first chapter of Felix Martin's Money: The Unauthorized Biography.