Separations are proceeding. Each alternative Zone speeds away from all the others, in fated acceleration, red-shifting, fleeing the Center. Each day the mythical return Enzian dreamed of seems less possible. Once it was necessary to know uniforms, insignia, airplane markings, to observe boundaries. But by now too many choices have been made. The single root lost, way back there in the May desolation. Each bird has his branch now, and each one is the Zone.

— Gravity's Rainbow by Thomas Pynchon (Page 519)