Now comes the second machine age. Computers and other digital advances are doing for mental power - the ability to use our brains to understand and shape our environments-what the steam engine and its descendants did for muscle power.

Because the process of innovation often relies heavily on the combining and recombining of previous innovations, the broader and deeper the pool of accessible ideas and individuals, the more opportunities there are for innovation.

Retailing has gone from an information-scarce to an information-rich environment.

Computers get better, faster than anything else ever. A child's PlayStation today is more powerful than a military supercomputer from 1996. But our brains are wired for a linear world. As a result, exponential trends take us by surprise. I used to teach my students that there are some things, you know, computers just aren't good at like driving a car through traffic.

Electricity is an example of a general purpose technology, like the steam engine before it. General purpose technologies drive most economic growth, because they unleash cascades of complementary innovations, like lightbulbs and, yes, factory redesign.

For a long time, the humans are going to be better than the machines and so different parts of the job will be leveraged. In a way that's happened for centuries, and we've adapted. And it's made the people who had parts of their jobs automated more valuable and more productive to the extent that they are essential for the other components of their jobs.

Technology is always creating jobs. It's always destroying jobs.