A history of civilization shares the presumptuousness of every philosophical enterprise: it offers the ridiculous spectacle of a fragment expounding the whole. Like philosophy, such a venture has no rational excuse, and is at best but a brave stupidity; but let us hope that, like philosophy, it will always lure some rash spirits into its fatal depths.
A great civilization is not conquered from without, until it has destroyed itself from within. The essential causes of Rome's decline lay in her people, her morals, her class struggle, her failing trade, her bureaucratic despotism, her stifling taxes, her consuming wars.
I think it's important to understand that in the big historical context of things, there has been land degradation from civilisation since the beginning of history. I mean, the Rajputana desert in India is a manmade desert caused by overgrazing.
Civilization is social order promoting cultural creation. Four elements constitute it: economic provision, political organization, moral tradition, and the pursuit of knowledge and the arts. It begins where chaos and insecurity end. For when fear is overcome, curiosity and constructiveness are free, and man passes by natural impulse towards the understanding and embellishment of life.