Nothing is durable, whether for an individual or for a society; the destinies of men and cities alike sweep onwards. Terror strikes amid the most tranquil surroundings, and without any disturbance in the background to give rise to them calamities spring from the least expected quarter. States which stood firm through civil war as well as wars external collapse without a hand being raised against them. How few nations have made of their prosperity a lasting thing!
-Seneca, Letter XCI from Letters from a Stoic