“An American is quite lost if he tries to think of the dollar as varying. He cannot easily think of anything by which to measure it. Even with our gold standard we have a dollar fluctuating in buying power. Yet we think of the dollar as fixed. It is fixed only in the sense that it is redeemable in a fixed number of grains of gold. It is not fixed in the amount of goods and benefits it can command.”
Irving Fisher, The Money Illusion (1928).