It's OK to have your eggs in one basket as long as you control what happens to that basket.

When Henry Ford made cheap, reliable cars people said, 'Nah, what's wrong with a horse?' That was a huge bet he made, and it worked.

The lessons of history would suggest that civilisations move in cycles. You can track that back quite far - the Babylonians, the Sumerians, followed by the Egyptians, the Romans, China. We're obviously in a very upward cycle right now and hopefully that remains the case. But it may not.

I don't spend my time pontificating about high-concept things; I spend my time solving engineering and manufacturing problems.

You need to be in the position where it is the cost of the fuel that actually matters and not the cost of building the rocket in the first place.

Boeing just took $20 billion and 10 years to improve the efficiency of their planes by 10 percent. That's pretty lame. I have a design in mind for a vertical liftoff supersonic jet that would be a really big improvement.

I hate writing about personal stuff. I don't have a Facebook page. I don't use my Twitter account. I am familiar with both, but I don't use them.