Macroeconomists, like medical scientists, use case studies to teach their students about the maladies to which the system is susceptible. For supply shocks and stagflation, the example is the 1970s. The financial dislocations that occur when bubbles burst are illustrated by the Great Depression and Japan's problems in the 1990s. The importance of central bank credibility in resisting inflation emerges from discussion of the experience of the late 1960s and the 1970s.

What is most remarkable and troubling about our current difficulties is that all these elements - supply shocks, financial dislocations and concern about rising underlying inflation - are present at once. Moreover, the crisis is global in scope. Concerns about recession are spreading from the US to much of the industrialised world. Significant slowdowns appear more likely in a number of emerging markets, with inflation concerns worldwide at their highest level in more than a decade. There is a growing consensus that the west is facing the most serious financial crisis since the second world war.