Eager-eyed Stephen Greenblatt, author of the just-published "Will in the World: How Shakespeare Became Shakespeare," is in a hidden-away room in the Folger Shakespeare Library, leaning over a table that contains three exquisitely rare 17th-century books -- a first folio of the plays, a copy of the first-known collection of sonnets and a pocket-size second quarto of "Hamlet." Books worth millions of dollars -- and much more.

In a charcoal suit, white shirt and thin blue tie, the willowy, dark-haired professor reaches for the leather-bound 1623 folio and flips to an engraving of Shakespeare. There is the mysterious man, a balding bard in a ruffed collar. On the page opposite is a short poem to the reader by Shakespeare's friend and rival Ben Jonson, wishing that the engraver could have captured Shakespeare's wit as well as his face.

But since he cannot, Reader, looke Not on his Picture, but his Booke.

"This is fantastic! This is the first time I've seen these copies," Greenblatt says. He did much of his research at the libraries of Harvard, where he has taught for eight years. The idea for "Will in the World" came from a conversation Greenblatt had years ago with Marc Norman, who was writing a screenplay that became the fanciful "Shakespeare in Love," starring Joseph Fiennes and Gwyneth Paltrow.

A first folio holds particular significance for Shakespeare scholars. Seven years after Shakespeare died, a couple of his actor pals compiled a collection of Shakespeare's plays -- 36 in all, half of which had never been published. Some 750 copies, or first folios, were printed: today 240 exist. The Folger owns 79. "Without this," Greenblatt says, holding a copy, "we wouldn't know about 'Macbeth.' "

Greenblatt knows all about "Macbeth" and the rest of the plays and sonnets. "Will of the World," his ninth book, has just been nominated for a National Book Award. He is also the editor of "The Norton Shakespeare."

Brought up in Newton, Mass., Greenblatt has degrees from Yale University and Pembroke College, Cambridge. Before Harvard, he taught at the University of California-Berkeley for 28 years. He is considered the godfather of the "new historicism," a branch of literary criticism that examines works of literature within their historic and social contexts. "I am constantly struck," he told the Harvard University Gazette, "by the strangeness of reading works that seem addressed, personally and intimately, to me, and yet were written by people who crumbled to dust long ago."

Still, there are always lingering questions about Shakespeare that even the most ardent devotee cannot answer. Greenblatt wrote the new book, he says, in an attempt to find out how "a young man from a small provincial town -- a man without wealth, without powerful family connections, and without a university education -- moves to London in the late 1580s and, in a remarkably short time, becomes the greatest playwright not of his age alone but of all time."

Greenblatt, 60, has spent his adult life piecing together that puzzle. And others. He turns to the 1609 first edition of the sonnets, and running a fingertip across the lines, reads: "To the onlie begetter of these insuing sonnets. Mr. W.H. All happinesse and that eternitie promised by our ever-living poet. Wisheth the well-wishing adventurer in setting forth. T.T."

This yellowed sheet of paper, Greenblatt says, "is the most enigmatic page in all of Shakespeare scholarship." It raises so many questions. Who was the begetter? Who was Mr. W.H.? William Herbert, the Earl of Pembroke? Or was it really H.W., Henry Wriothesley, the Earl of Southampton? And -- the most basic query of all -- who was Shakespeare?

Greenblatt has heard all of the theories -- that the works of Shakespeare were written by Sir Francis Bacon, the Earl of Oxford, Queen Elizabeth or somebody else.

And during his visit here to promote his book, he entertains some of the questions again. When he speaks to a gathering of the Folger faithful one evening or to callers on a radio show or to fellow scholars as he strolls through the library's reading room, Shakespeare fanatics pose ultimately unsolvable riddles.

Was the playwright secretly a champion of Catholicism? Greenblatt says he believes that Shakespeare was a "fundamentally secular spirit." He turns in the first folio to the end of "The Tempest" and reads:

With the help of your good hands:

Gentle breath of yours my sails

Must fill, or else my project fails,

Which was to please. Now I want

Spirits to enforce, art to enchant,

And my ending is despair,

Unless I be relieved by prayer,

Which pierces so that it assaults

Mercy itself and frees all faults.

As you from crimes would pardon'd be,

Let your indulgence set me free.

That is the language of prayer, Greenblatt says. But it's not a petition to God, it's an appeal to theatergoers for love and applause. Shakespeare channeled any religious views he might have had into his theatrical vision. He believed in a higher authority, Greenblatt says: drama.

Were Shakespeare's plays meant to be read as well as performed? Greenblatt raises this question himself. Recent literature, such as last year's "Shakespeare as Literary Dramatist" by Lukas Erne, suggests that Shakespeare wrote his plays for readers and for actors. Greenblatt's not completely buying it. "Shakespeare wrote more than a company could use in a given performance," he says. The playwright expected lines and soliloquies and whole scenes to be axed from the final script. Unlike Jonson, Shakespeare was apparently not that wedded to his written works, Greenblatt says. After all, the Bard gave his plays trifling names such as "As You Like It" and "Twelfth Night, or What You Will."

Did Shakespeare really write all those glorious things? Greenblatt believes he did. Reaching for the folio, he points to all the people -- Jonson, John Heminge and Henry Condell -- who signed pages in the first folio. "They would all somehow have to be involved in this fantastic conspiracy," Greenblatt says. Then shaking his head: "Not very well likely."

At one point he says, "The other-person thing never worked for me." And implications that Shakespeare was not educated enough to write such masterpieces -- because he did not go to Oxford or Cambridge university -- Greenblatt says, "were always dismissive and full of snobbery."

The ultimate Shakespeare question is the one that Greenblatt addresses in "Will of the World." How on Earth did one man write such truth-filled and timeless literature?

For one thing, Greenblatt says, Shakespeare didn't shy away from any subject. Unlike many other male European hotshots, Shakespeare "thought that blacks, difficult women, homosexuals and Jews might be interesting to write about."

For another, Shakespeare "didn't play by the rules." He wrote of royalty, gentlefolk and commoners alike, probing their hearts and desires, giving his works the fullness of life. And when it came to traditional forms of drama, he mixed it up. "The French at the time had strict rules for what a tragedy had to include or a comedy," Greenblatt says. "With Shakespeare, tragedies bled into comedies. Even today, the French see Shakespeare as a vulgarian."

Other countries were shaken by Shakespeare. At one point, Georgianna Ziegler of the Folger Library brings out a copy of a 1632 second folio that once belonged to an English college in Valladolid, Spain. A censor from the Holy Office had scratched out certain words -- such as "codpiece" -- and whole passages here and there. The entire play "Measure for Measure" was ripped out, perhaps because it makes light of Catholic notions.

"People do things to sacred texts," Greenblatt says.

For many people there is something sacred about Shakespeare. Even the ever-rational Greenblatt will admit as much. Saint Paul, he says, felt that certain parts of the Old Testament, written centuries earlier, were written for him. "Shakespeare has that effect on people."

So why is that? Could it be the result of something we in the 21st century have completely lost touch with: inspiration?

Greenblatt is not discounting the notion that something -- mortal or not -- inspired Shakespeare to write so well. He says he's pretty sure, however, it wasn't Gwyneth Paltrow.

Whatever jolted Shakespeare into genius will remain a mystery. Greenblatt says the real magic lies not in the man, but in the work.

In a way, he harks back to Jonson's first folio dedication:

Reader, looke Not on his Picture, but his Booke.

In the end, the ultimate mystery surrounding Shakespeare is not that, after all these centuries, we know so little about him, but that, after all these centuries, he knows so much about us.

The author of "Will in the World: How Shakespeare Became Shakespeare."Greenblatt, at the Folger Shakespeare Library, believes Shakespeare wrote all the works attributed to him. "The other-person thing never worked for me," he says.