Where inflation ALWAYS comes from

"There is perhaps no empirical regularity among economic phenomena that is based on so much evidence for so wide a range of circumstances as the connection between substantial changes in the quantity of money and in the level of prices." ... "It follows ... that inflation is always and everwhere a monetary phenomenon in the sense that it is and can be produced only by a more rapid increase in the quantity of money than in output."  --Milton Friedman, quoted in Judy Shelton, Money Meltdown (New York: The Free Press 1994), p. 176 & 177