Osama bin Laden, the Saudi-born revolutionary who is believed by most Arab and Iranian observers to be the inspiration of the attacks in New York and Washington, is the best known of the Islamic militants to have emerged in the past 20 years and the least difficult to fathom.

The use of refined petroleum as fuel, which began in the 1850s, freed hundreds of millions of people from the toil of centuries, gave hundreds of millions more a life of ease and plenty, and, by allowing great cities to feed themselves from every corner of the world, multiplied the population of the earth fivefold.

Bulls don't read. Bears read financial history. As markets fall to bits, the bears dust off the Dutch tulip mania of 1637, the Banque Royale of 1719-20, the railway speculation of the 1840s, the great crash of 1929.

Losing your capital is like losing your trousers. It is a real humiliation, and one not to be soon repeated.

When Gordon the Brown, in London in 1997, commissioned a great inquisition or survey of his new realm, the result was the so-called national asset register (NAR), which was immediately dubbed by the boomers of the UK Treasury "the modern Domesday Book".

Life without oil, in fact, would be so different that it is frightening to contemplate. We are addicted, and it is no comfortable addiction.

What holds an Arab leader in power is a mixture of violence and prestige. Both President Assad and King Hussein were felt to have defended Arab interests against the world. That, in the end, is more important than what they wear on their head.