NOVA

Leonardo da Vinci.

Legendary artist.

His genius is universal.

It speaks to everybody.

He was also a scientist and inventor.

There was a reason for every decision

and every line.

How did he create

the most famous painting on Earth?

You can perceive the beating of the pulse

underneath her skin.

The answers have been as elusive as her smile.

Leonardo embraced mystery.

Now researchers are peeling away the layers.

Thanks to a new kind of scientific investigation,

we are really able to get inside the painting.

Can science unlock her secrets?

She seems like she's alive,

because she looks different

depending on where you're looking.

And decipher the genius behind her creator?

"Decoding da Vinci,"

right now, on "NOVA."

Major funding for "NOVA" is provided by the following:

In the heart of Paris lies a former royal castle.

It is now the world's busiest art museum:

the Louvre.

Filled with glorious galleries

of antiquities, mummies, and Michelangelos.

But one masterpiece is the biggest draw of all.

Today's reigning queen...

the "Mona Lisa," by Leonardo da Vinci.

The "Mona Lisa" has become

some grand thing in our imagination.

Each time you see the "Mona Lisa,"

you have a different feeling

about what she has in mind.

Every year, millions visit her,

drawn by her beauty

or, perhaps, her fame.

They've clocked the average amount the visitors

spend looking at the "Mona Lisa,"

and that's roughly about 15 seconds.

You're more focused on getting a good picture

for your Instagram feed

than actually looking at the painting.

So is the "Mona Lisa" just famous

for being famous?

More icon than art?

Or does she deserve her place on the Louvre's throne

as the most celebrated painting in the world?

It's not just a portrait

of a woman who was living 500 years ago.

It's a demonstration of how painting could show life.

Now researchers are using new techniques

to investigate the most famous painting on Earth

like never before.

The smile is crucial.

It's teasing you, saying,

"I know something you don't know."

Could the "Mona Lisa," with her enigmatic smile,

be the key to decoding the man who made her...

Leonardo da Vinci?

No doubt he was a brilliant artist,

but he was also a groundbreaking scientist.

He anticipated theories by both Galileo and Newton

by at least a century.

And dreamed up remarkable inventions

that seem to predict our modern age:

armored tanks,

flying machines,

even something like a self-driving car.

But were his scientific explorations

a distraction from his painting?

Or was science the secret to his artistic genius?

Was the "Mona Lisa," in fact, Leonardo's greatest invention?

If you want to understand Leonardo da Vinci,

you just have to look at the "Mona Lisa,"

because it's all there.

It's the culmination of a lifetime spent

loving science and art.

In the back streets of Florence, Italy,

Valter Conti and his daughter Elena

prepare for their tribute to Leonardo

and the "Mona Lisa"...

Human statues handing out Leonardo quotes.

It's their way of marking the 500th anniversary

of Leonardo's death,

and just one of many celebrations

that are in the works around the world.

From a fine art museum in Beijing

to a multimedia extravaganza in Peru...

And a blockbuster exhibition at the Louvre.

For the Louvre museum,

it's a really important moment.

Because Louvre is like Leonardo da Vinci.

We have the third of all his paintings.

Vincent Delieuvin oversees the five Leonardo masterpieces

that hang at the Louvre.

That's the largest collection in the world.

While Leonardo may be

the most famous painter of all time,

he completed surprisingly few paintings.

Leonardo was really someone experimental.

He didn't want to paint a lot.

He wanted to paint a perfect painting.

So what did it take

for Leonardo to make a perfect painting?

The answer may be lying right under Delieuvin's feet.

For the upcoming exhibition,

he is working with a team of scientists

housed downstairs from the Louvre,

at the Center for Research and Restoration

of Museums in France.

Thanks to a new kind of scientific investigation,

we are really able to get inside the painting

and to understand how Leonardo was working

to perfect the painting

for a long, long time... during five, ten, 20 years.

It's really something really specific to Leonardo.

They are peering deep inside Leonardo's masterpieces,

hoping to reveal the secrets of his technique

that our eyes cannot see.

The eye sees something

that it believes to be two-dimensional,

but which is really three-dimensional,

because there is depth in a painting.

For art historian Bruno Mottin,

the first step is to understand

the chemistry of Leonardo's paint,

starting with the powdered minerals

that were the source of his colors.

You have green, which is made

with the scratching of copper plates,

you have vermillion, which is made with mercury,

you have lead white, which is made with lead.

But these can't be applied directly on a painting...

it has to be mixed with something else.

These colored pigments

are mixed with a liquid, like oil.

That gets painted on in layers.

In a cross-section of a painting,

you have the base-

which today is frequently canvas,

but in Leonardo's time, they used planks of wood.

On that is a coat of white that can reflect light.

As the artist works, semi-translucent paint

is built up layer by layer

and then sealed with a coat of varnish.

In the end, our eyes see the interplay

between the light reflected off different pigments

suspended in the layers,

creating depth and elusive subtleties.

Oil is a translucent medium,

which gives to the mixture a deepness.

You can see through all the layers.

You don't only see a flat surface.

You have the feeling of what is beneath the painting.

Leonardo worked on the "Mona Lisa" for about 16 years.

Can these investigative techniques

help reveal, ultimately, what he was doing all that time?

The "Mona Lisa" began in Florence, Italy, in 1503

as a commission from a wealthy cloth merchant

to paint his wife, Lisa Gherardini.

The word "mona" was a polite form of address,

much like "madam," hence "Mona Lisa."

Over time, she became something much more.

The "Mona Lisa" started off as a portrait for a merchant's wife

and ended up as a sort of manifesto, if you want,

of his ability as a, as a painter,

of his conception of the world, even.

So is this what the real Lisa looked like?

And how different does she appear today

from what Leonardo painted 500 years ago?

To find out, scientists captured the "Mona Lisa"

with an array of high-tech cameras.

These detect light in the electromagnetic spectrum

that is not visible to our eyes.

So just as some cameras can see wildlife in the dark,

these cameras can help us

see the "Mona Lisa" in a new light...

literally.

Each image provides clues about her past.

So we have a lot of different images,

which can tell us

about the structure of the painting

and the, the way it has been made.

In the ultraviolet image,

blotches of dark blue appear.

These reveal areas of paint

which are not by Leonardo's hand.

They are modern restorations to repair damage to the painting,

like this dangerous crack in the wood base.

And for Mottin, it reveals even more.

It shows us that the painting is in fact colored

by a greenish and yellowish varnish

which changes the colors of the true painting.

This thick varnish has yellowed and darkened over time,

making it difficult to make out some of the details.

She looks rather like a plump lady, we should say,