It is a question that has foxed art lovers for centuries: Why the hell is the Mona Lisa as bald as a coot in the eye brow department?
The answer to which you won't find here.
But there is a (slightly less interesting) question which we may be able to shed some light on thanks to a slightly eccentric French inventor spending 3,000 hours studying UV images of the picture: where they are.
Like a street walker the mysterious one's eye brows and lashes are hidden under layers of paint according to Parisian engineer Pascal Cotte who claims to have a special infared and ultraviolet scanning machine.
Mssr Cotte said his ultra-detailed digital scans of the painting allow him to effectively burrow through layers of paint to "see" into the past of Leonardo Da Vinci's 16th-century portrait of a Florentine merchant's wife.
The world's most famous painting originally included both brows and lashes, according to Cotte, who said his 240-megapixel scans reveal traces of Mona Lisa's left brow, obliterated by long-ago restoration efforts.
"With just one photo you go deeper into the construction of the painting and understand that Leonardo was a genius," Cotte said at the US debut of an exhibit detailing his findings.
Not only has Mona Lisa got hidden facial hair says Cotte but the emotional push-me-pull-you was definitely smiling.
Da Vinci also changed his mind about the position of two fingers on the subject's left hand and she is also holding a blanket that has all but faded from view today.
For more information go to:
http://www.monalisarevealed.com
In terms of things to worry about, this is probably quite low on my list - certainly hasn't been keep me up at night!