6 ideas
The proper subject of history is how whole peoples lived, meaning their laws, arts, commerce, beliefs and daily customs, rather than the battles and successions of rulers. Shifting attention from courts to societies shows that the durable changes in human life come from slow shifts in mentality and practice, not from the deeds of individual monarchs.
A universal history must begin with China, India and the Islamic world, because these civilisations were older, more populous and often more refined than medieval Europe. Treating Europe or the biblical narrative as the axis of world history is a provincial distortion that collapses once other peoples' records and achievements are taken seriously.
Voltaire holds that a common core of reason and natural morality exists in all peoples, while custom produces the enormous surface diversity of rites, dress and law. Nature makes humans alike and custom makes them different, so whatever is shared across cultures points to the natural core and whatever varies is local convention.
Voltaire presents imperial China as an ancient state run by lettered officials, grounded in a morality without revealed dogma and in continuous historical records. The example shows that social order and ethics can rest on reason and tradition rather than priestly authority, which undercuts the claim that Christianity is necessary for civilisation.
Crusades, inquisitions, religious wars and massacres such as St Bartholomew's Day show that zealous dogma, together with clerical ambition for power, caused more human misery than almost any other force. Superstition goes hand in hand with cruelty, and the spread of reason and toleration is the main remedy.
Voltaire explains events through natural causes such as climate, government, commerce, accident and human passions rather than through God's plan for salvation. Once divine purpose is removed as an explanatory device, history turns into a contingent record of human folly and progress that can be judged by reason.