As I write, the damage and death-toll of the latest earthquakes in China are being assessed, and the inhabitants of New Orleans are returning to the city from which they fled a few days ago, happy (one assumes) that Hurricane Gustav has been less destructive than was expected. ‘Events’, said Bismarck, ‘are stronger than the plans of men’, and even in our technologically advanced civilisation Nature frequently reminds us of her ability to provide terrifying and destructive events. The eruption of Mount Vesuvius in AD 79, which engulfed the towns of Pompeii and Herculaneum, was, in comparison with some of Nature’s other efforts, comparatively unremarkable.

If it is now remembered, when so many other natural accidents have been forgotten, it is first because of the eyewitness account ‘in a couple of letters written a quarter of a century after the event to the historian Tacitus by his friend Pliny who had been staying on the