05/28/2013 05:39 pm ET Updated Jul 28, 2013

Platonism and Secularism in the Thought of Plethon

Byzantium (medieval Greece) survived the barbarian invasions that brought the Western Roman Empire to an end in the fifth century. Medieval Greece lived for more than a millennium, for several centuries a superpower. In fact, medieval Greece spread civilization to Eastern Europe and Russia.

Medieval Greece, however, had enemies in the Christian West and the Moslem East. The Christian crusaders dismembered Greece in 1204. Greece never recovered from that blow. Eventually, the Turks reaped the fruits of crusading violence against Greece. They occupied the country in 1453.

The first half of the 15th century was a time of tragedy for the Greeks. Western states and the Turks in particular occupied most of Greece.

During this time of upheaval -- not too dissimilar from the Western economic occupation of Greece in the second decade of the 21st century -- a Greek Platonic philosopher by the name of George Gemistos Plethon inspired and led a Renaissance of ancient Greek culture in Peloponnesos, the southern heart of Greece.

Plethon was born around 1355 in Sparta. He died in 1452. He was convinced that the Greeks could defend Peloponnesos. He told the emperor to be bold: time for Christian business as usual had expired. Ditch Christianity and revive the religion of ancient Greece, Plethon said. In the emergency the Turks had created, nothing but a national Greek army could save the independence of Greece. The wealth of the church could fund the defense of the country.

Second, inspired by Plato, Plethon proposed the abolition of the private ownership of land. Each family would have the right to a modest plot of land for raising its own food. But the moment the tillers of the soil ceased to farm, the land reverted to the state. That way Plethon abolished hunger, poverty, farm workers, and large farmers.

Plethon also drew from the intellectual vision of Plato who had made clear that man had the intelligence to understand both society and the cosmos. Man required neither sacred texts nor extraterrestrial intervention for achieving intellectual and moral perfection. His mind could make him godlike. It was this Platonic idea of reason and the science it inspired that made our world.

Plethon taught near Sparta in Peloponnesos with Plato at the core of his teachings. He asserted the cosmos is both sacred and "imperishable." It "has no beginning in time nor will it ever cease to exist." His instruction inspired a Greek Renaissance that challenged Christianity's existence in Greece.

This happened in the midst of a catastrophic decline in the power of Greece. Her enemies, both domestic and foreign, were formidable. The church would have nothing to do with the "pagan" ideas of Plethon. Indeed, the man who served as the first patriarch under the Turks, George Scholarios, burned the "Laws," the most important work of Plethon.

Niketas Siniossoglou, a Greek philosopher, studied Plethon. In his "Radical Platonism in Byzantium: Illumination and Utopia in Gemistos Plethon" (Cambridge, 2011), he concluded Plethon was the culmination of centuries of Greek resistance to Christianity. Plethon's vision of a resurrected Greek republic in Peloponnesos, with all the gods and virtues of ancient Greece, was more than a utopia: it was an act of supreme courage and wisdom. Hellenism had the power of enlightenment and patriotism.

By close to mid-15th century, the Turks were at the gates. Yet Orthodox bishops made no secret they would rather see Turkish turbans to the hat of the pope in their midst. The desperate emperor, who appreciated the advice of Plethon, agreed to the union of the Orthodox and Catholic churches, hoping this would bring Western military aid. However, Orthodox opposition wrecked the union.

It was this internal civil war, Orthodox Christianity's fierce resistance to both Hellenism and the West, which explain Plethon. He turned to Hellenism for the courage to fight the Turks. His dream of a dechristianized Greece remains a dream for the Greeks to recover their Hellenic inheritance, injecting Christianity for the gods.

In 1453, however, the Turks occupied Constantinople, thus assuring the survival of Christianity in Greece.

Siniossoglou documents the contributions of Plethon beyond Peloponnesos. What Plethon did was fundamental: He dechristianized Plato and Aristotle, which opened the gates to our modern world. Suddenly, paganism, meaning the reading of Greek texts without Christian glasses, became modernity. The Western European immersion in the Greek texts sparked the growth of science and technology and the development of a new non-Christian metaphysics of human perfectibility.

Plethon separated church and state. He proposed a national army; and reason, he said, rather than faith, ought to fuel and be the arbiter in the development of science and society.

Plethon's secularism, especially the dechristianization of Hellenic thought, had more influence, according to Siniossoglou, in post-Renaissance Europe. Thinkers like Baruch Spinoza (1632-1677), Saint-Simon (1760-1825) and Auguste Comte (1788-1857) followed up with Plethon's dethronement of Christianity and proposed their secular visions of society. Plethon also foreshadows ultra-radical Jacobins, quixotic heretics, and Marxists.

Read Siniossoglou's tremendously important book -- a timely marvel of scholarship and insight -- that illuminate the contributions of Plethon to the secularism of our Western civilization.