Roman History

"Before the destruction of Carthage, the people and the Senate of Rome together governed the Republic peacefully and with moderation. But when the minds of the people were relieved of that dread, wantonness and arrogance naturally arose, vices which are fostered by prosperity."

Gaius Sallustus Crispus - 1st century BC

Quoted after David Levering Lewis, God's Crucible: Islam and the Making of Europe, 570-1215 (He quoted it after another, obscure book).