The gradual decline of a society is often a self-induced process of trying to meet ever-expanding appetites, rather than a physical inability to produce past levels of food and fuel, or to maintain adequate defense.
“Throughout the centuries, man has considered himself beautiful. I rather suppose that man only believes in his own beauty out of pride; that he is not really beautiful and he suspects this himself; for why does he look on the face of his fellow-man with such scorn?”