Balance sheets matter. This is the biggest lesson of the financial crises that have rolled across the world economy. Changes in balance sheets shape the performance of economies, as credit moves in self-fulfilling cycles of optimism and pessimism. The world economy has become credit addicted. China could well be the next victim.

If we think about balance sheets in the world economy of today, four questions arise. First, what determines vulnerability? Second, where are vulnerabilities now appearing? Third, how are countries coping with the legacy of old debt crises? Finally, can the world economy cope with the new vulnerabilities?

Start with the sources of vulnerability. In economies with liberalised financial sectors, the driver towards disaster is far more often private than public imprudence. Rising property prices and expanded mortgage lending drive many credit booms. A deterioration in the public sector’s balance sheets usually then follows crises. Failure to recognise this link between private excess and public borrowing is wilful blindness.