The Renaissance
In the wealthy city-states of Italy, a rediscovery of classical Greek and Roman learning — much of it preserved and advanced in the Islamic world, and some carried west by scholars fleeing Constantinople — sparked an explosion of art, science, and a new confidence in human possibility. Merchant money from banking families like the Medici paid for Leonardo, Michelangelo, and the rest. It is what happens when a flood of recovered ideas meets a flood of new money: not a single invention, but a change in what people believed they were permitted to think.
A belief system rises, spreads, institutionalizes, and then schisms — changing the rules people accept as legitimate.