But man discovered, in the process of trial and error, the route that permits a greatly-expanding economy: indirect exchange. Under indirect exchange, you sell your product not for a good which you need directly, but for another good which you then, in turn, sell for the good you want. At first glance, this seems like a clumsy and round-about operation. But it is actually the marvelous instrument that permits civilization to develop.

The emergence of money was a great boon to the human race. Without money—without a general medium of exchange—there could be no real specialization, no advancement of the economy above a bare, primitive level. With money, the problems of indivisibility and “coincidence of wants” that plagued the barter society all vanish. Now, Jones can hire laborers and pay them in... money. Smith can sell his plow in exchange for units of... money. The money-commodity is divisible into small units, and it is generally acceptable by all.

Now that we have seen how money emerged, and what it does, we may ask: how is the money-commodity used? Specifically, what is the stock, or supply, of money in society, and how is it exchanged?

If the size or the name of the money-unit makes little economic difference; neither does the shape of the monetary metal. Since the commodity is the money, it follows that the entire stock of the metal, so long as it is available to man, constitutes the world’s stock of money. It makes no real difference what shape any of the metal is at any time.

How did money begin? Clearly, Robinson Crusoe had no need for money. He could not have eaten gold coins. Neither would Crusoe and Friday, perhaps exchanging fish for lumber, need to bother about money. But when society expands beyond a few families, the stage is already set for the emergence of money.