The last test of genius is its longevity. But in thinking about what comes next, it's remarkable to note how young Apple's new celebrity is. The iPod is only ten years old. A child born on the day the iPhone debuted in 2007 wouldn't yet be in kindergarten. A child born on the day the iPad debuted in 2010 might not be walking.

Still, great companies occasionally flat-line. Microsoft had the largest market cap in history in 2000 and its stock hasn't increased over the last ten years. GE's has declined. But Jobs leaves his company surprisingly well positioned. Even as the first or second most valuable company in the world, Apple's price-earnings ratio is normal to low. Its products are too superior, its potential in overseas market too big, and the global mobile tech space too fecund for Apple to face imminent decline.

Predicting what comes next is prophecy. Suffice it to say that having reinvented the personal computer, music business, phone, and personal computer (again), Steve Jobs has demonstrated and re-demonstrated his genius for us. In return, we wish him well.