I carried two psychological burdens on the promotional tour for my book earlier this year. One was the knowledge that a competitor is published every thirty seconds; every day I was on the road, the ranks of new titles swelled by 2,880. My second burden was awareness that Rick Warren’s ‘The Purpose Driven Life’ sold 500,000 copies a month during its first two years, and is projected to reach 100 million. I found it hard to accept that my own book might not sell quite so well. Now I at least know how Rick does it: He has built a ‘Cellular Church’ that is based on small groups for whom his book is a kind of primer. As Malcolm Gladwell explains in this week’s New Yorker (12 September) Rick’s small groups ‘focus on practical applications of spirituality…not on abstract knowledge, or even on ideas for the sake of ideas themselves’.