" As stable as it may seem on the surface to some, the current configuration of the global economy and the financial system is getting harder to maintain. Below the façade of the unusual calm of the last few years, interrupted by relatively few bouts of instability since 2008–09, tensions are rising and the effectiveness of central banks is coming under stress, so much so as to raise serious questions about the durability of the current path that the global economy is on. "

― Mohamed El-Erian , The Only Game in Town: Central Banks, Instability, and Avoiding the Next Collapse