New book "The Swerve," a gripping tale of an ancient poem that conveys the cosmos

'It's not the Da Vinci Code," says Stephen Greenblatt, "but it tells the same story: the thrill and astonishment when something very old, something thought to be lost, forgotten, returns to the world with the potential to change it."

Greenblatt - who reads at 7:30 p.m. Thursday at the Central Library - is speaking of his new book, The Swerve: How the World Became Modern. He's right: Swerve isn't much like Dan Brown's Da Vinci Code. The latter is a fantasy potboiler. (Not that there's anything wrong with that; it's one of the most sensational successes in publishing history.)

But Swerve is an intense, emotional telling of a true story, one with much at stake for all of us. And the further you read, the more astonishing it becomes. It's a chapter in how we became what we are, how we arrived at the worldview of the present. No one can tell the whole story, but Greenblatt seizes on a crucial pivot, a moment of recovery, of transmission, as amazing as anything in fiction.

What's recovered, crazily enough, is a tattered copy of an epic philosophical poem written two millennia ago (at least 55 B.C.) by the Roman poet Lucretius (full name, Titus Lucretius Caro). Its traditional name is De Rerum Natura (On the Nature of Things), and it's one of the wonders of world poetry.

It also was a dangerous poem - in any society that required belief in gods. It posits a cosmos of atoms eternally in motion, of human life without gods or an afterlife. It says wisdom resides in the enhancement of pleasure and avoidance of pain. And it sees in the contrarious and unpredictable nature of reality a "swerve," an almost willful jump, which sounds a lot (to some readers) like the indeterminability of quantum physics.

This masterwork anticipated much that materialist, empirical, scientific people now think about the universe.

"The direct inheritors of Lucretius," Greenblatt says from his office at Harvard, where he is professor of English and American literature, "turn out to be everyone who lives in this world - everyone who gets an MRI, or flies in an airplane, or lives in a world of nuclear power, or lives in a country that cares about enhancing the happiness and diminishing the sufferings of everyone."

But Lucretius almost did not survive. His poem was praised in its own time, but when Rome fell, it, too, descended into oblivion.

"I wanted to bring out the urgency of it," Greenblatt says, "of what was at stake. I often think about how much might have been different had it never been found. I wanted the reader not to lose the startle reflex."

So - not unlike Humberto Eco, who in The Name of the Rose set a murder mystery in the unlikely world of medieval monks - Greenblatt tells a gripping tale of . . . scholarship, of a Renaissance book-hunter who travels hundreds of miles from Italy to a monastery in Northern Europe, where in 1417, he recognizes and rescues what was all but the last trace of Lucretius.

Poggio Bracciolini is the name of the book-hunter, an energetic and many-talented man whose portrait is one of the best things about Swerve. Once Poggio helps transmit the near-lost poem to the world, a powder trail is sparked in minds centuries into the future. Lucretius grazes off Machiavelli, Montaigne, Giordano Bruno, Shakespeare, Galileo, Darwin, Einstein.

The book ends with Thomas Jefferson writing the phrase pursuit of Happiness in the Declaration of Independence - a Lucretian moment that helped fledge this very country.

"We really have lost, or almost lost, two things," says Greenblatt. "It's the poetic and visionary power of Lucretius, and it's the Renaissance that's at risk of getting lost."

Again like Name of the Rose, Greenblatt's book is for a general readership, and it's written by a scholar longing to reach a wider public. In his own field, Greenblatt is (and this is no exaggeration) one of the most influential writers of his moment. He is often called the inventor of the New Historicism, a way of reimagining history and its impact.

But something happened, and Greenblatt the scholar became Greenblatt the best-selling author.

"After decades of writing for a scholarly audience," he says, "I began to feel frustrated that I couldn't communicate how beautiful and urgent our work often is." Out of that frustration, he wrote Will in the World (2004), a brave revisionist biography of Shakespeare that became a New York Times best seller and sold more than 150,000 copies. Scholars bridled at its way of patching evidence gaps with imaginative leaps. Too bad for them.

Swerve is much in the same line. It links things and people and minds not normally thought of as linked. Greenblatt sees Lucretius' influence in the Botticelli painting Birth of Venus, and also in Machiavelli's The Prince. Some readers would see the two as very different. But Swerve makes a persuasive case that, in today's view of the cosmos, "much that Lucretius imagined has been borne out," Greenblatt says.

What of the reader who lives in 2011 but does not subscribe to all of Lucretius, all that Greenblatt identifies as modern? "It's never been necessary to buy into every one of his propositions," Greenblatt says. "If it were, we couldn't live the lives we live. There are a lot of intermediate positions. I light Sabbath candles and bless my son. I don't appeal to Lucretius for exemption. After all, he himself begins his poem with a prayer to Venus. He says, 'Fine. If such rituals enhance your sense of pleasure and wonder in existence, do them, do them.' "

Pleasure and wonder: They are what the Lucretius of Swerve offers. And his ideas and poetry helped many of history's greatest thinkers think freely, joyfully, courageously forward for themselves. That is the swerve of free will, the human swerve born of the cosmic swerve of The Swerve.