Christina Romer

As an economic historian, I appreciate what manufacturing has contributed to the United States. It was the engine of growth that allowed us to win two world wars and provided millions of families with a ticket to the middle class. But public policy needs to go beyond sentiment and history.

A successful argument for a government manufacturing policy has to go beyond the feeling that it's better to produce 'real things' than services. American consumers value health care and haircuts as much as washing machines and hair dryers.

Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it's hard to make it pay off - Moon bases are expensive, and just buying more rockets to launch fuel from Earth is relatively cheap.

My venture investing career has three phases, all roughly 6-8 years long. The first, at Euclid, was software to Internet. The second, at Flatiron, was Internet to bubble. And the third, at USV, has been web 2 to mobile. I have always used a new firm to denote a new investment phase for me. Throw away the old. Start with the new.