Finally.
The theory is that inflation of the money supply leads to inflation in prices.
Except that the oft-mentioned multiple years of QE (which some see as inflating the money supply) didn't lead to any significant runup in prices of anything anyone measured. What it might have done is to remove a portion of the toxic debt infusing the general economy at the time, thus preventing a deflation in the value of tangible assets, and possibly a depression of which no one dared predict the bottom.
What amuses me is that the Republicans (who have traditionally included the people who know most about managing money - at least according to the Republicans) let this happen, and the Democrats saved us from it.