Here is what I don't understand:

What is to stop the FED from just continuously buying debt? I mean, it could do it indefinately so long as the velocity of money remained steady and interest rates remained near zero. You just buy up your own treasuries through third parties. You could, technically, do it forever if the truth was concealed so that others wouldn't catch on and make a rush for the exits.

So, again, what is to stop the Treasury and FED from just printing as needed and gobbling up the vast majority of it's own debt without ever stopping?