But the broader lesson of the first Industrial Revolution is more like the Indy 500 than John Henry: economic progress comes from constant innovation in which people race with machines. Human and machine collaborate together in a race to produce more, to capture markets, and to beat other teams of humans and machines.

Going a little further into the future, we'll start literally connecting to machines. Some of my colleagues at MIT here - some of them are working on a neural mesh that connects directly to your brain, and they've already done it with some disabled people and allowed them to move objects just by thinking.

It's most useful to think about not jobs but tasks. And within any given job, there are lots of different tasks. If you're a radiologist maybe reading the images machines can be able to do that better, maybe making the broader diagnosis and communicating it to the patients.

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.

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.

Technology has made it easier for different firms to coordinate their activities with one another, and they don't have to be part of one company. They can get the benefits of scale without the inertia of scale.

G.D.P. is not a measure of how much value is produced for consumers. Everybody should recognize that G.D.P. is not a welfare metric.