Ancient Greece, birthplace of Western civilization, was contradictory. It produced the first known thinkers who tried to understand the world through logic and observation instead of through supernatural explanations. Yet it also had thousands of animal sacrifices to supposed gods on Mount Olympus, and people gave gold to mystical "oracles" who babbled in trances.

One of the foremost logical thinkers was Epicurus (341-270 B.C.), who taught that there's no actual evidence for miracles or afterworlds, so people simply should lead rewarding lives here and now. He also speculated that all matter consists of invisible atoms swerving endlessly and that creatures change through evolution.

A couple of centuries later, Roman thinker Lucretius (99-55 B.C.) wrote a long tribute to Epicurus titled De Rerum Natura (On the Nature of Things). His classic poem was cited by various other ancient writers, but all copies of it were lost.

Then, nearly 15 centuries later, a scholarly papal clerk, Poggio Bracciolini, visited a German monastery in 1417 and found a long-forgotten copy covered by dust on a remote shelf. Elated, he began distributing handwritten copies to European intellectuals, who discussed the Lucretius work in learned forums. It spurred a breakthrough for scientific thinking.

Distinguished Harvard University professor Stephen Greenblatt contends that rediscovery of the lost Lucretius poem helped trigger the Renaissance, the Age of Reason, the Enlightenment, and the six-century upsurge of science and democracy that catapulted the West into today's advanced civilization.

His book, The Swerve: How the World Became Modern, won a 2012 Pulitzer Prize and a National Book Award. It's creating a buzz in intellectual circles.

Of course, nobody thinks the rediscovery of a single lost Latin poem by itself transformed international culture -- but the 15th century episode obviously was a factor in the great mental shift that grew with the Renaissance. It was a milestone on the vast journey humanity has traveled.

Contemplating how the modern mentality evolved is intriguing.