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.

Computers get better faster than anything else ever.

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.

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.

Knowing how to keep someone motivated and how to keep a connection are skills humans have learned and evolved over hundreds of thousands of years. A robot can't figure out whether you can do one more push-up, or how to motivate you to actually do it.

We're rapidly entering a world where everything can be monitored and measured. But the big problem is going to be the ability of humans to use, analyze and make sense of the data.

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.