“When people scoff at sending humans to Mars, and say that pictures of wheel marks on a red desert are not worth the trouble when there are so many things here at home that we could be spending money on, it makes me claustrophobic. It’s as if we’re trying, out of guilt or shame, to crawl back into the cave and watch the shadows on the wall. We’re trying to stay children in our parents’ house, knowing that the road leads to town, and then to another town. We’re saying, “Look, we made a really great toilet that flushes itself! Remember that printing press? That was pretty neat. We even made pyramids — those things are huge! Can’t we just be happy with making a great toilet even greater? Do we really have to go to Mars?” But Mars is waiting. It spins now outside our human reach. We must realize that the work of growing up is not something we can cut when the budget gets tight. It is mission critical, for the intellectual life of the species, for the future of humans, not to stagnate, not to wither, but to stretch, and reach, and always to expand.”