It must be admitted that there is a degree of instability which is inconsistent with civilization. But, on the whole, the great ages have been unstable ages. – Alfred North Whitehead

Civilization is a limitless multiplication of unnecessary necessaries. – Mark Twain, quoted in More Maxims of Mark compiled by Merle Johnson, 1927

Barbarism is needed every four or five hundred years to bring the world back to life. Otherwise it would die of civilization. – Edmond and Jules de Goncourt, Journal, 3 September 1855

Leash: n, a means by which animals, formerly running wild, are prevented from running tame, also. – Robert Brault, rbrault.blogspot.com