For decades, he wrote, advanced economies were losing their ability to grow by making useful things. But they needed to somehow replace the jobs that had been lost to technology and foreign competition, and to pay for vote-winning entitlements. So to pump up growth, governments spent more than they could afford and promoted easy credit to get households to do the same.

Predictably, this proved unsustainable. Without politically painful supply-side reform to correct these failings, we can look forward to years of stagnation or worse. Central banks may have succeeded in preventing a repeat of the Great Depression, but they cannot correct these underlying deficiencies. 

--Financial crisis: the printing press has reached its limits, The Telegraph