National boundaries are not evident when we view the Earth from space. Fanatical ethnic or religious or national chauvinisms are a little difficult to maintain when we see our planet as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and citadel of the stars. Travel is broadening.
Sagan, C., Druyan, A. and Tyson, N. deGrasse (2013) Cosmos. New York: Ballantine Books.
