"Wonderful," Lepennon said, and his white skin paled further with pure excitement, "A human society with an effective war-barrier! What's the cost, Dr Lyubov?"
   "I'm not sure, Mr Lepennon. Perhaps change. They're a static, stable, uniform society. They have no history. Perfectly integrated, and wholly unprogressive. You might say that like the forest they live in, they've attained a climax state. But I don't mean to imply that they're incapable of adaptation."

– Ursula K. Le Guin, The Word for World is Forest