Who was the Mona Lisa? It would be the most intriguing mystery in the history of art - if we didn't basically already know the answer.
A note in one of Leonardo da Vinci's books was discovered in 2005, which confirmed that he was working on a portrait of Lisa del Giocondo. Also known as Lisa Gherardini, she was the wife of a wealthy Italian silk merchant.
But still, the theories pile up. The Mona Lisa was a man, or an adapted self-portrait, or Leonardo's mother…
So, to settle the debate once and for all, Italian researchers are planning to dig up bones in a Florence convent, believed to be the final resting place of Gherardini, and use reconstruction techniques to see if the face matches the painting. They really won't let this one lie.
In fact, the researcher who wants to lead the dig is the very same Italian who has made something of a name for himself with outlandish claims about the Mona Lisa. In December, Silvano Vinceti posited that Leonardo had left clues to the Mona Lisa's identity by painting initials in her left eye. At the time, the art historian Donald Sassoon told The National that this latest theory was "brilliantly silly".
Vinceti wasn't put off, though, and in February claimed that the model was actually one of Da Vinci's male muses. So maybe he's just wanting to rule Gherardini out of his investigations, CSI-style.
Still, however groundless all these theories are, they're proof that the Mona Lisa hasn't become such an important painting simply because it's a masterpiece of technique. The mystery behind her identity means she can be whoever and whatever the viewer wants her to be. It was the writers of 19th-century France who decided she was a seductress, not the art historians. The story stuck. The Mona Lisa, then, is a classic example of how art often becomes "great" because of the narrative behind it, rather than merely the look of a painting itself.
Take another Leonardo: the epic The Last Supper. Technically it is everything one would want from a masterpiece. But it's the theories that have sprung up around The Last Supper that have tended to make it a must-see. Is the person to Jesus's right Mary Magdelene or the Apostle John? Who knows, but Dan Brown managed to fashion The Da Vinci Code around the idea that the body angles in the painting spuriously fashion the letter M.
Of course, all good art has to have something to grapple with, otherwise it's meaningless. In fact, some work is all about the narrative: Tracey Emin's notorious My Bed tells a story about her life, even if you wouldn't exactly want to show it off in your front room.
Damien Hirst's shark in formaldehyde makes little sense, essentially, until you read the title of it: The Physical Impossibility of Death in the Mind of Someone Living. Immediately, this preserved creature of the deep became a commentary on mortality. Art is naturally all about interpretation, but the danger in encouraging the myths surrounding works such as the Mona Lisa and The Last Supper is that the desire to understand - or create a story about - a painting becomes more important than the work itself.
Are we looking at Vincent van Gogh's Sunflowers because they're superb examples of post-impressionism, or because we're trying to look for evidence of his much-documented madness? Happily, there are rare occasions where the masterpiece and the message are of equal importance. Pablo Picasso's Guernica depicts the bombing of the Basque capital in April 1937 during the Spanish Civil War. Just a month later, probably the world's most famous artist at the time had completed Guernica, full of writhing people and animals.
It's become perhaps the anti-war painting, hung in tapestry form in the United Nations building and posted on billboards by protesters during the war in Iraq. The original has pride of place at the Museo Reina Sofia in Madrid.
And yet Picasso said at the time: "I make the painting for the painting. If you give a meaning to certain things it may be very true, but it is not my idea to give this meaning." And because he worked in this way, Guernica succeeds, spectacularly, as a classic piece of 20th-century art rather than merely a heavy-handed commentary on the bombing of innocent civilians.
There's still enough in the painting to speculate or theorise on, which is important. As the industry surrounding the Mona Lisa proves, we actually seem to like not knowing everything. Despite what Silvano Vinceti might think.
* Ben East