Rothbard

Private individuals and businesses must either sell something of value to acquire money or expend time and resources to mine it directly (think of gold mining in the case of a gold standard). Governments, in contrast, do not obtain payment for goods or services they produce; they generate revenues through the seizure of assets. In the past, they might have sent their agents to seize grains, cattle, coins, etc. from people. But in a monetary economy, they simply seize monetary assets, which is a lot easier to do. ...

In a free banking system, various banks issue their own banknotes which are redeemable for the gold that they hold. The banks set their policies independently and compete with other banks in the free market. This is distinct from the central banking system we experience today, where a central bank dictates key requirements the chartered banks must obey, and these banks issue a single fiat currency. One important decision a bank needs to make in a free banking system is how much reserves it shall hold on to at any moment to meet the withdrawal demands of the depositors. If the reserves are less than 100% of the deposits, the bank engages in fractional reserve banking. (Setting aside the question of morality of such a system, free banks with fractional reserves have emerged in the free market and operated for a long time in the past.) ...

Before discussing fractional reserve banking, let’s go over the concept of full reserve banking. Suppose a bank takes in total deposits worth $100 million from its depositors. The bank promises the depositors that they may withdraw their deposits anytime. The bank, in this case, simply acts as a warehouse for the money deposited, collecting fees from the depositors in return. At any time, all deposited money remains within the bank; and at any time, any or all depositors may come to collect the money they have deposited. This is full reserve banking: all the deposits remain in reserve. ...

Note that the law applies not just to a particular type of coins, but to the exchange rates between different money commodities as well. Suppose in a bimetallic standard, metal A is pegged to metal B at a ratio of 1:10, but the market value of a unit of metal A is 12x that of metal B. In this case, we have a price ceiling whereby metal A is artificially undervalued, and per Gresham’s Law, will be driven out of circulation. ...

Gresham’s Law is frequently oversimplified as “bad money drives good money out of circulation.” This phenomenon has been observed in history whenever debasement of coins has occurred. In such cases, people choose to collect coins with the greater precious metal content and spend the debased coins. Over time, the ‘good’ money, the coins with more precious metal in them, get driven out of circulation by ‘bad’ money, the debased coins. ...