Matt Yglesias visits the world of Westeros to make a brilliant point about why tangible goods are so much more important than gold:
[I]n Westeros, the Lannisters have the cube of gold and the Tyrells with the rich farmland of the Reach have the real resources. You can’t eat gold. You can’t feed it to your horse either. Gold doesn’t keep you warm during those lengthy winters. Gold is useful primarily because it’s a convenient medium of exchange (who wants to carry all that wheat around) and a durable store of value (keeping a whole bunch of horses alive and healthy is itself a resource intensive process). So people with claims over valuable real resources will often end up accumulating gold. But though the Lannisters have more gold than anyone else, that’s not how they got their gold. They just own gold mines.
Now don’t get me wrong, you’d rather own gold mines than not own them. But the ability to pull shiny metal out of the ground is trivial compared to the power of a well-fed army. Imagine a scenario in which the Westerlands are out of food, and the Reach is out of gold. The Tyrells and their bannermen will need to curtail their consumption of luxury goods until they can manage to sell food for gold, but the austerity will be survivable if a bit unpleasant. The Lannisters, by contrast, are going to find that if they try to trade a whole big pile of gold for a whole big pile of food that the price of food will skyrocket. The illusion of Lannister wealthy is based on the idea that we can take the marginal price of an ounce of gold, then multiply that by the total quantity of the Lannister gold supply, and then conclude that the Lannisters are hyper-wealthy. In reality, any effort to mobilize all that metallic wealth will lead to inflation rather than the ability to mobilize vast quantities of real resources.