Any sufficiently radical invention seems ridiculous to most people when they first encounter it. This is a rule of technological innovation.

In 1998, I ate lunch with an entrepreneur at a vegetarian restaurant in San Francisco. The entrepreneur, an ascetic and a yogi with startling blue eyes, spooned a lone bowl of bean soup and told me, "Software is a living tree." He said he had invented a new kind of software called PowWow that "would allow people to run in tribes on the Internet." He boasted that Tribal Voice, his new venture, would be the physical manifestation of what Indian shamans call "the golden thread." I was nonplussed.

Yet Tribal Voice could not be immediately dismissed, because the entrepreneur was John McAfee, the founder of the antivirus company McAfee Associates, for some years the most profitable company on earth. In 1989, when McAfee Associates was starting up, its business seemed as ridiculous as Tribal Voice did in 1998. It gave away its most important program, VirusScan, and sold licenses and support to corporations. This idea had made John McAfee supremely rich.