Ten years ago Sargent and Wallace [1981] provided with the simple and elegant analysis that has now become the classic "unpleasant monetarist arithmetic": a fall in the rate of monetary expansion without a corresponding fall in the primary deficit is not only doomed to be transitory, but will eventually bring about an inflation rate higher than before the change. The reason is of course very simple: there is limit to government debt, and eventually not only the transitory stabilization will be called off, but at that time a higher rate of monetary growth (and inflation) will be needed to finance not only the same primary deficit than before the change, but also the higher flow of interest payments on the stock of government debt accumulated in the interim.