I remember once sitting cross-legged on the floor of a terraced house in North London and staring into the impassive features of a fashionable oriental guru. I was trying to interview the man, but he insisted on treating me like a disciple, responding to every question with a finely-honed aphorism and a benign smirk. I was suffering from a hangover that morning, and the guru's otherworldly serenity was a tremendous reproach to my own self-indulgence. Afterwards a little cloud of guilt and spiritual unease settled over me. It did not evaporate until, a few weeks later, I opened a newspaper to read that two of the guru's female followers were suing him for sexual assault.

I was not really surprised. Most of us, deep down, are suspicious of saintly ascetics, and with good reason. As Anthony Storr demonstrates in Feet of Clay, many gurus have serious problems with sexual continence: at times one suspects that they only wear those flowing robes because they are constitutionally incapable of keeping their flies buttoned up. Neither the Bhagwan Shree Rajneesh nor David Koresh could keep their hands off their younger female disciples, and even Jung slept with two of his patients. The Revd Jim Jones, meanwhile, believed that he was the only truly heterosexual male in Jonestown, and alleged that many of the other males had not come to terms with their homosexuality. 'To demonstrate this,' reports Dr Storr, 'he found it advisable to bugger some of them.'

Storr does not shrink from describing the gross indignities to which many gurus have subjected their followers. But the harrowing descriptions of life in Jonestown, Waco and the Rajneesh ranch in Oregon are by no means its most disturbing feature.