Inflation

"Inflation is a tax on money. Like any tax, it will be used. The more subtle, the less detected, and the less avoidable the tax, the better it is for those with predominant political power and the more surely it will be used."
-Don Boudreaux

"Progressive deterioration in the value of money through history is not an accident, and has had behind it two great driving forces -- the [desire of governments to spend] and the superior political influence of the debtor class."
-John Maynard Keynes's 1923 book, Tract on Monetary Reform