consider gold to be a commodity (easy to do, because it is), shipping it overseas, you're engaged in trade, exporting gold, importing stuff or foreign currency. But nobody holds currency, because "time value of money", you want to hold something that yields income.
Indeed! Money is a special kind of a commodity, at least initially. With fiat money, it's more complicated, but still. All trade is barter trade, in a sense.
Money, e.g. gold, has a very special quality: it's accepted in exchange for any goods. It's the ultimate "narrow waist" of goods exchange. This gives money a very special status among commodities.
