People can't anticipate how much they'll miss the natural world until they are deprived of it. I have read about submarine crewmen who haunt the sonar room, listening to whale songs and colonies of snapping shrimp. Submarine captains dispense 'periscope liberty'- a chance to gaze at clouds and birds and coastlines and remind themselves that the natural world still exists. I once met a man who told me that after landing in Christchurch, New Zealand, after a winter at the South Pole research station, he and his companions spent a couple days just wandering around staring in awe at flowers and trees. At one point, one of them spotted a woman pushing a stroller. 'A baby!' he shouted, and they all rushed across the street to see. The woman turned the stroller and ran.