This is the best, simplest explanation of the reasons the gold standard is so profoundly broken. Are you listening, Ron Paul?
In short, there is a really serious problem inherent in any banking system in which the standard is itself a medium of exchange. The very fact that gold is money means that, in any fractional reserve system based on gold, there is an inherent tendency for the system to implode when there is a loss of confidence in bank money that causes a shift in demand from bank money to gold. In principle, what would be most desirable is a system in which the monetary standard is not itself money. Alternatively, the monetary standard could be an asset whose supply may be increased without limit to meet an increase in demand, an asset like, you guessed it, Federal Reserve notes and reserves. But that very defect is precisely what makes the Ron Pauls of this world think that the gold standard is such a wonderful idea. And that is a scary — as in terrifying — thought.