Ernest Gellner (1925-1995), Nations and Nationalism
, 2nd ed. (Malden: Blackwell Publishing Ltd., 2006), p. 50:
Agrarian man can be compared with a natural species which can survive in the natural environment. Industrial man can be compared with an artificially produced or bred species which can no longer breathe effectively in the nature-given atmosphere, but can only function effectively and survive in a new, specially blended and artificially sustained air or medium. Hence he lives in specially bounded and constructed units, a kind of giant aquarium or breathing chamber.