Voltaire's best-known histories are "History of Charles XII" (1731), "The Age of Louis XIV" (1751), and his "Essay on the Customs and the Spirit of the Nations" (1756). He broke from the tradition of narrating diplomatic and military events, and emphasized customs, social history and achievements in the arts and sciences. The "Essay on Customs" traced the progress of world civilization in a universal context, rejecting both nationalism and the traditional Christian frame of reference. Influenced by Bossuet's "Discourse on Universal History" (1682), he was the first scholar to attempt seriously a history of the world, eliminating theological frameworks, and emphasizing economics, culture and political history. He treated Europe as a whole rather than a collection of nations. He was the first to emphasize the debt of medieval culture to Middle Eastern civilization, but otherwise was weak on the Middle Ages. Although he repeatedly warned against political bias on the part of the historian, he did not miss many opportunities to expose the intolerance and frauds of the church over the ages. Voltaire advised scholars that anything contradicting the normal course of nature was not to be believed. Although he found evil in the historical record, he fervently believed reason and expanding literacy would lead to progress.