Assuming constant velocity, inflation is caused by the difference between the growth in the money supply and growth in real output. (money.stackexchange.com)
Sometimes, it is difficult to disentangle the effects on real output from simultaneous supply and demand shocks. (businessinsider.com)
When people are feeling more conservative and want to hoard cash or rebuild their balance sheets, you can inject more money into the system and it doesn't bid up the prices of real output because everybody wants to hold more cash rather than spend it or invest it. (judithcurry.com)