It is hard to find a period in the post-war era in which inflation-adjusted interest rates have been so low for so long and monetary and credit aggregates have expanded so much without igniting inflation (the "Great Liquidity Expansion puzzle"). What lies behind these developments? How benign are they? This paper argues that financial liberalisation, the establishment of credible anti-inflation monetary policies and (real-side) globalisation have resulted in subtle but profound changes in the dynamics of the economy and in the challenges faced by policymakers. In the new environment which has gradually been taking shape, the main "structural" risk may not be so much run away inflation. Rather, it may be the damage caused by the unwinding of financial imbalances that occasionally build up over the longer expansion phases of the economy, typically spanning more than one higher-frequency business cycle. Depending on its intensity, the unwinding can lead to economic weakness, unwelcome disinflation and possibly financial strains. The analysis has implications for monetary and prudential policies. It calls for a firmer long-term focus, for greater symmetry in policy responses between upswings and downswings, with more attention being paid to actions during upswings, and for closer cooperation between monetary and prudential authorities. In recent years, the intellectual climate and policy frameworks have gradually evolved in a direction more consistent with this perspective. At the same time, obstacles to further progress remain. They are of an analytical, institutional and, above all, political economy nature. Removing them calls for further analytical and educational efforts.