No place on earth is more baby-boomerish than Silicon Valley, and Jobs was its avatar: a CEO who wore jeans and emitted a “reality distortion field,” a sentimental, countercultural romantic who was also a ruthless mogul, a forever-young tinkerer dedicated to erasing the old distinctions between tools and toys, work and play.

Jobs had a genius for building group identity. He handed out distinctive T-shirts and offered such childish but effective incentives as buying pineapple pizza for everyone if they completed a particularly difficult task by a certain time. He shrouded their work in mystery, insisting that no outsider be told what they were up to. The Macintosh was t