Does high inflation harm a country's economy? How does this happen?

If you knew for certain how fast the currency was going to inflate you could price forward to compensate for it. Under those assumptions, why would it be GOOD for a country to have an inflating currency? The answer is that inflation is a game governments play to surprise markets so that wealth is transferred from those who don't anticipate it to those who do. Government is the biggest beneficiary of inflation because so much of its revenue comes from a progressive tax scheme where people whose nominal, but not real, incomes rise pay ever increasing amounts of tax to the government.