What we did in that review article is look at what is known and what science and engineering can deliver.

We can readily address, with research, 30% of current transportation-fuel needs. But reaching that goal will require five to 10 years and significant policy and technical effort.

There is only one nature - the division into science and engineering is a human imposition, not a natural one. Indeed, the division is a human failure; it reflects our limited capacity to comprehend the whole.

Progress depends on the unreasonable man.

Stephenson had large wrought-iron boiler plates available and he also had the courage of his calculations... The idea found its best-known expression in the Menai railway bridge opened in 1850. Stephenson's beams, which weighed 1,500 tons each, were built beside the Straits and were floated into position between the towers on rafts across a swirling tide. They were raised rather over a hundred feet up the towers by successive lifts with primitive hydraulic jacks. All this was not done without both apprehension and adventure; they were giants on the earth in those days.

As you can imagine, they've been very helpful, because being in space is all about math, science and engineering.