The economy is the money creation, the money stock and the exchange rate. If the currency is too weak this leads to inflation and if the currency is too strong this leads to unemployment. If the exchange rate is too strong it encourages the creation of money in foreign countries and this is inflation. If the exchange rate is too weak this discourages the creation of money in foreign countries and this is unemployment.
In addition a country that runs out of currency will go into a deflation, meaning the prices will start falling. Deflation, if not managed properly can end up in an eventual collapse of the economy. If you have deflation at the same time you have inflation you get a zero interest rate. In fact, if the interest rate is always zero, an economy will be doomed. In order to avoid this situation governments must spend and the central bank must create money to stimulate the economy.
