A century ago, petroleum - what we call oil - was just an obscure commodity; today it is almost as vital to human existence as water.

Ever since the destruction of Baghdad by the Mongols in 1258, the Muslim world has been in slow decline relative to the west. With Napoleon's invasion of Egypt and the creeping British annexation of Muslim India, that decline took on a malign aspect.

Whatever else it was, Adolf Hitler's short-lived regime was also a colossal industrial process by which the wealth and productive power of much of Europe was wrenched from its normal purposes and converted into a machine for killing.

When William the Conqueror commissioned a great survey of his English realm at Gloucester in 1085, the result was a work so thorough, fair, dispassionate, and wide-ranging that it seemed to the succeeding generations to have come from another world.

Of all the failed technologies that litter the onward march of science - steam carriages, zeppelins, armoured trains - none has been so catastrophic to prosperity as the last century's attempt to generate electricity from nuclear fission.

A century ago, petroleum - what we call oil - was just an obscure commodity; today it is almost as vital to human existence as water.

Europe and North America, we are told, are less dependent on energy-intensive heavy industry than in the 1960s and 1970s. It seems we squeeze more GDP out of a barrel of oil than in those benighted days.