Decoding da Vinci | Full Documentary | NOVA | PBS

♪ ♪ NARRATOR: Leonardo da Vinci. Legendary artist. VINCENT DELIEUVIN: his genius is universal. He talks to everyone. NARRATOR: He was also a scientist and inventor. KARLY BAST: There was a reason for every decision and every line. NARRATOR: How did you create the most famous painting on Earth? FRANCESCA BORGO: You can feel the beat of his pulse under his skin. ♪ ♪ NARRATOR: The answers have been as elusive as her smile. Leonardo embraced the mystery. NARRATOR: Now researchers are peeling back the layers. DELIEUVIN: Thanks to a new kind of scientific research, we can really get into the picture. NARRATOR: Can science unlock its secrets?

MARGARET LIVINGSTONE: She looks like she's alive, because she looks different depending on where you look. NARRATOR: And decipher the genius behind its creator? "Decoding da Vinci", right now, on "NOVA". ♪ ♪ ♪ ♪ NARRATOR: In the heart of Paris lies an ancient royal castle. Now it is the most popular art museum in the world - the Louvre. Full of glorious galleries of antiquities, mummies and Michelangelo. ♪ ♪ But a masterpiece is the greatest attraction of all. Today's reigning queen: Leonardo da Vinci's "Mona Lisa." WALTER ISAACSON: The "Mona Lisa" has become something great in our imagination. DELIEUVIN: Every time you see the "Mona Lisa," you get a different feeling about what she has in mind.

NARRATOR: Every year, millions visit her, drawn by her beauty or, perhaps, her fame. BORGO: They've calculated the average time visitors spend looking at the "Mona Lisa," and that's about 15 seconds. You're more focused on getting a good image for your Instagram account than looking at the painting. NARRATOR: So the "Mona Lisa" is famous simply for being famous? More icon than art? Or does it deserve its place on the Louvre's throne as the most famous painting in the world? DELIEUVIN: It's not just a portrait of a woman who lived 500 years ago. It is a demonstration of how painting could show life.

NARRATOR: Now researchers are using new techniques to investigate Earth's most famous painting like never before. ♪ ♪ MARTIN KEMP: Smiling is crucial. She's teasing you by saying, "I know something you don't know." NARRATOR: Could the "Mona Lisa," with her enigmatic smile, be the key to deciphering the man who created her: Leonardo da Vinci? He was undoubtedly a brilliant artist, but also an in

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tive scientist. He anticipated the theories of Galileo and Newton by at least a century. And he came up with remarkable inventions that seem to predict our modern era: armored tanks, flying machines, and 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? ISAACSON: If you want to understand Leonardo da Vinci, you just have to look at the "Mona Lisa," because it's all there. It is the culmination of a lifetime dedicated to the love of science and art. ♪ ♪ NARRATOR: On 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 quotes from Leonardo. It is their way of commemorating the 500th anniversary of Leonardo's death, and just one of many celebrations being prepared around the world.

From a fine arts museum in Beijing to a multimedia show in Peru... And a highly successful exhibition at the Louvre. DELIEUVIN: For the Louvre museum, it's a really important moment. Because the Louvre is like Leonardo da Vinci. We have the third of all the paintings of him. NARRATOR: Vincent Delieuvin oversees the five Leonardo masterpieces that hang in the Louvre. ♪ ♪ That is 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 much. He wanted to paint a perfect picture. ♪ ♪ NARRATOR: So what did Leonardo need to make a perfect painting?

The answer may be right under Delieuvin's feet. For the upcoming exhibition, he is working with a team of scientists housed on the ground floor of the Louvre, at the French Museum Research and Restoration Center. DELIEUVIN: Thanks to a new kind of scientific research, we can really delve into the painting and understand how Leonardo worked to perfect it for a long, long time: five, ten, twenty years. It's really something very specific to Leonardo. NARRATOR: They are looking deep inside Leonardo's masterpieces, hoping to reveal secrets of his technique that our eyes cannot see. BRUNO MOTTIN: The eye sees something that it thinks is two-dimensional, but that is actually three-dimensional, because there is depth in a painting. (phone rings) NARRATOR: 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.

MOTTIN: You have green, which is made by scratching copper plates, you have vermilion, which is made with mercury, you have lead white, which is made with lead. But these cannot be applied directly to a paint: they have to be mixed with something else. NARRATOR: These colored pigments are mixed with a liquid, such as oil. That is painted in layers. ♪ ♪ In a cross section of a painting, you have the base, which today is usually canvas, but in Leonardo's time wooden boards were used. On top of that is a white layer that can reflect light. As the artist works, the semi-translucent paint is built up layer by layer and then sealed with a layer of varnish.

Ultimately, our eyes see the interaction between light reflected by different pigments suspended in the layers, creating depth and elusive subtleties. MOTTIN: Oil is a translucent medium, which gives depth to the mixture. You can see through all the layers. You don't just see a flat surface. You get the feeling of what's underneath the painting. NARRATOR: 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 way of addressing her, much like "ma'am", hence "Mona Lisa". Over time, it became something much more. BORGO: The "Mona Lisa" began as a portrait of a merchant's wife and ended up being a kind of manifesto, if you will, of his ability as a painter, even of his conception of the world. NARRATOR: So this was what the real Lisa looked like? And how different does it look today from what Leonardo painted 500 years ago? (Device hum) To find out, scientists captured the "Mona Lisa" with a series 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 to his past. MOTTIN: We have many different images that can tell us about the structure of the painting and the way it was made. NARRATOR: Dark blue spots appear in the ultraviolet image. These reveal areas of painting that are not by Leonardo's hand. They are modern restorations to repair damage to the paint, such as this dangerous crack in the base of the wood. And for Mottin, this reveals even more. MOTTIN: It shows us that the painting is actually colored by a greenish and yellowish varnish that changes the colors of the real painting.

NARRATOR: This thick varnish has yellowed and darkened over time, making it difficult to make out some of the details. She looks like a plump lady, we would say, because we don't know where her arm ends. NARRATOR: But this infrared image clearly shows that this dark area was once translucent. Lisa wears a veil that falls grace

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y over her surprisingly thin shoulders. ♪ ♪ To penetrate the deeper layers, the team turns to a tool we're more familiar with in the doctor's office: X-rays. These can reveal how the painting began. Most artists of the time started with a drawing and then filled it with thick paint.

The x-ray looks like this, "La Belle Jardinière" by Raphael. The numbers started out clearly defined and stayed that way. ♪ ♪ But when Leonardo's paintings are x-rayed, the figures often disappear. ♪ ♪ ELISABETH RAVAUD: Leonardo's image is like a ghost. At first glance we do not understand what is really in the image. NARRATOR: In the X-ray of the "Mona Lisa", there is no clear outline. Instead, the image evolved as Leonardo made continuous adjustments. This also suggests that Lisa may not have looked exactly like this. ISAACSON: He keeps it. He does not deliver it to the merchant who ordered it.

Because for him it is no longer a portrait of the Mona Lisa. It is a universal painting. ♪ ♪ NARRATOR: At the next exhibition, Delieuvin plans to hang some of these scientific masterpieces alongside Leonardo's original paintings. The scans demonstrate an essential point about Leonardo's art: he painted like no one else. DELIEUVIN: Leonardo is one of the first truly free artists. He felt free to change his mind, not only during the preparation of the drawing, but also during the painting of his work. This is incredibly rare. He is the only one who gives such freedom, such freedom, in the execution of it. ♪ ♪ NARRATOR: Artists then were considered artisans and needed to produce paintings for their patrons.

So how did Leonardo become such a free spirit? From the beginning, Leonardo was an outsider. ♪ ♪ Born in 1452, the son of a single farmer in the small Italian town of Vinci, he was called "Leonardo de Vinci." Therefore, Leonardo da Vinci. ISAACSON: Leonardo was very lucky to be born out of wedlock. It meant that he hadn't gorged on that sort of dusty old scholastic wisdom from the Middle Ages. Instead, he became self-taught. It also meant that he didn't have to be a notary like his father. And so he has a new life, where he can be whatever he wants. ♪ ♪ NARRATOR: At about age 14, Leonardo's father sent him to learn a trade in Florence, the epicenter of commerce, learning, and beauty in the early Renaissance.

PAOLO GALLUZZI: Florence was one of the most advanced social organizations on the planet. Very rich city. A city that attracted the brightest kids around. (bicycle bell rings) KEMP: Florence is just extraordinary right now, for producing Donatello, Masaccio, Brunelleschi, Michelangelo, Raphael. ♪ ♪ NARRATOR: With no formal education, Leonardo began as an apprentice in one of the leading artists' studios of the time: the workshop of Andrea del Verrocchio. Verrocchio was above all a sculptor, but also a painter and architect. He could play music. ♪ ♪ So Verrocchio's example was very important for Leonardo. Leonardo's training with Verrocchio is a real model of how an artist should evolve.

The technique is subordinated to the act of seeing. It is about the eye, and it was Leonardo who described it for the first time. NARRATOR: The beautiful model for this statue of David by Verrocchio is believed to be his apprentice, a young Leonardo. So they think that Leonardo posed for his teacher. It's a very elegant baby face framed by these beautiful curls. NARRATOR: Despite the circumstances of his illegitimate birth, the workshop gave Leonardo a way to get ahead in life. ISAACSON: He's a misfit. He is illegitimate. He is gay, left-handed, vegetarian, absent-minded, and yet the people of Florence welcome him because he was a very tolerant city.

NARRATOR: One of the most challenging construction projects of the day was topping off the dome of the impressive cathedral with a golden sphere. The commission to crown the dome with a golden sphere was very important. And that's a commission that Verrocchio got. NARRATOR: Verrocchio's team, which included a young Leonardo, had to figure out not only the design, but also how to secure the one-and-a-half-ton ball to the top of the nearly 370-foot-high cathedral. ISAACSON: Figuring out how to get the ball to the top of the cathedral helps Leonardo become a great engineer. He helps him become an artist, because he correctly grasps the perspective of the ball.

That combination of science, engineering and art becomes part of who Leonardo da Vinci is. NARRATOR: In fact, in great quantity, Leonardo's scientific research far exceeds his pictorial production. Proof of this is a remarkable collection of replicas of his notebooks. GALLUZZI: We have very few records, in the entire history of science, similar to Leonardo's manuscripts. These are not books. You cannot compare that with a work by Galileo or Newton, because they solved the problems before writing their books. NARRATOR: Paolo Galluzzi is the director of the Galileo Museum in Florence. GALLUZZI: What we have in Leonardo is the direct expression of his internal dialogue.

NARRATOR: Leonardo's notebooks cover his entire life. They even come in pocket size. BORGO: We are sure that those 6,000 pages we have are his. And this is only a quarter of what he actually wrote. So we are talking about something that obsessed him throughout his life. NARRATOR: The brilliance and breadth of Leonardo's notebooks is astonishing. His ideas seem to predict ourmodern era, making Leonardo much more than a Renaissance scientist to many. His dreams of human flight include a helicopter-like machine and a parachute. The fascination with water gave rise to ambitious civil engineering proposals. ♪ ♪ And he conceived an intriguing self-propelled machine that looks part automobile and part primitive robot.

But could any of these inventive designs really have worked? JOHN OCHSENDORF: Leonardo is, of course, a great artist, but he is also a great scientist and, I would say, a great engineer. The geometry is impressive... NARRATOR: A small sketch in Leonardo's notebooks has so intrigued MIT. Engineer John Ochsendorf asked his graduate student Karly Bast to apply the rigor of 21st-century engineering to see if Leonardo's 16th-century idea would actually hold up. OCHSENDORF: There is a historical reason for this, because you see it in the drawing, right? BAST: Yes, these two are not... NARRATOR: In 1502, the year before starting the "Mona Lisa", Leonardo proposed to the sultan of the Ottoman Empire a bridge in Constantinople five times longer than any other span of the time. . ♪ ♪ His plan for this ambitious project, sketched backwards in a small notebook, offers few details... but enough for Bast to bring it to life.

Leonardo provided four measurements, but he provided two sketches. At first it looks like a sketch, but as I dug deeper into it, I realized there was a reason for every decision and every line. A lot of thought went into force distribution, and it wasn't just aesthetic. It was engineering. NARRATOR: And to test that engineering, Bast and his colleagues built a scale model of the bridge with a state-of-the-art 3D printer. MOHAMED ISMAIL: Before 3D printing came along, we had to try to build that bridge as close to

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scale as possible, because you couldn't reliably get the geometry right.

NARRATOR: Leonardo's stone bridge would have been 500 times larger than this model, but the physics are exactly the same. BAST: We have the bridge and we have the mold that supports it. The first piece should be easy to remove. NARRATOR: Piece by piece, he removes the Styrofoam, a modern substitute for the wooden scaffolding used in Leonardo's time. OCHSENDORF: This is more like heart surgery than building a bridge. NARRATOR: Finally the last support is removed. ♪ ♪ And Leonardo's stone bridge remains standing. OCHSENDORF: The geometry is aesthetically beautiful and the fact that it stands on its own tells us that it was feasible.

BAST: Absolutely. OCHSENDORF: Wow. NARRATOR: Leonardo's bridge remains even when they simulate an earthquake. Arrest. LOPAN: 1,500 pounds. OCHSENDORF: Oh my God. It has been moved 30 feet and the arch still stands. NARRATOR: The bridge eventually collapses, but only after having been moved the equivalent of 50 feet. Leonardo has the artistic ability, and he also has that scientific knowledge and that engineering ability that allows him to create beautiful and structurally sound things. NARRATOR: Bast clearly had to fill in some details to get from this sketch to this model. And we do not know if the bridge could have been built with the wooden scaffolding of the time.

And it also shows... NARRATOR: But she has shown that Leonardo understood basic physics well. OCHSENDORF: What's extraordinary is the ideas he came up with more than 500 years ago. Yes. OCHSENDORF: We're still trying to understand them. ♪ ♪ NARRATOR: As with this ambitious proposal to the sultan, Leonardo sought wealthy patrons throughout his life to support not only his art, but also his scientific explorations. At the age of 30 he moved to Milan to work for his duke. 17 years later, when the duke was deposed, Leonardo had to move once again, back to Florence and, later, to Rome. His achievements in science and art meant that he had much to offer.

ISAACSON: Leonardo sells himself as an engineer, as well as an artist, because he knows that he can make a better living. But I also think Leonardo loved the connection between the arts and sciences, and he didn't want to see himself isolated simply as a painter. NARRATOR: Leonardo's scientific explorations can also be clearly seen in the details of his paintings. He studied everything from botany to the physics of running water. Even the curls of human hair. DELIEUVIN: To paint something absolutely perfect, he had to understand how nature was made. To paint a mountain, to paint rocks, he had to understand why the rocks were that type.

He was obsessed with it. And that was what he called the science of painting. NARRATOR: The science of painting was all-encompassing for Leonardo. But how could he capture in paint the beauty he observed in nature? ♪ ♪ Back at the Louvre, conservators and art researchers are uncovering new clues in an elegant intensive care unit for priceless works of art. ♪ ♪ To prepare for the upcoming exhibition, Delieuvin and the team of scientists are restoring a painting that has long been mired in controversy. For centuries, this portrait of Bacchus was considered one of the few paintings made by Leonardo. But now experts aren't so sure. (speaks French) DELIEUVIN: For centuries, that painting was attributed to Leonardo.

But during the 20th century, some historians said, "Well, it seems like a difference compared to the other paintings." NARRATOR: Cinzia Pasquali has been brought in to restore the painting. Can Leonardo's unique scientific techniques provide him with the clue he needs to finally solve the mystery: Did Leonardo really paint this? (speaks French): PASQUALI: (both speak French) NARRATOR: Restoration work is not for the faint of heart. This painting may be in poor condition, but Pasquali continues to take her scalpel to an irreplaceable masterpiece. He removes the darkened yellow varnish, revealing a vibrant color underneath. (speaking quietly) NARRATOR: But other parts of the painting seem more damaged.

That is why Pasquali must trust in her training not only in art history, but also in chemistry. ♪ ♪ Paint pigment colors may change or fade over time. But the chemistry of the pigments can still be detected. Pasquali commissions a special scan for the element copper, often used in green paint. The scan reveals that this dark area of ​​the painting was once a lush garden, until the copper of the painting darkened. PASQUALI: So we can see a lot of vegetables, leaves, plants and flowers, and when you look at the surface of the work, they are not. NARRATOR: While the beauty of these plants may suggest Leonardo's meticulous attention to detail, that is not enough to say with certainty that he painted them himself.

So the investigation focuses on his brushstrokes. One of the most characteristic fingerprints of a Leonardo are remarkably thin layers of paint, which can only be seen with a powerful microscope. NARRATOR: Some Leonardos have been discovered to have up to 30 layers of paint, many more than most painters. As he continues his restoration, Pasquali searches for evidence of this unusual technique. But what was Leonardo trying to achieve with all those thin layers? Ask a living painter. FLORENT FARGES: Da Vinci was always looking for beauty. He doesn't just paint or draw a tree. He wants to paint the perfect expression of what a tree is.

This aspiration to beauty is, for me, very inspiring as an artist. (birds singing) NARRATOR: Florent Farges is a painter in Dijon, France. Following the tradition of the Renaissance, Farges runs an artist's workshop, but with a different touch. FARGES: Hello everyone and welcome to a new video. NARRATOR: Yours is virtual. FARGES: This will guide you through the entire process of painting classical figures. NARRATOR: Most Italian painters of the time mixed their pigments in an egg base, using real egg. But egg tempera doesn't let in as much light, so there is less depth in the painting. Instead, Leonardo decided to use an oil, such as linseed or walnut.

DELIEUVIN: Leonardo was using oil. Because oil paint helps to reproduce the transition between light and shadow in the best way. NARRATOR: Little by little, Farges' portrait comes to life. ♪ ♪ For the finishing touches, Farges demonstrates how oil paint can be applied in a very thin layer to create a subtle hue of light falling on the human body. FARGES: If I want, I can come back later and put another layer on top so that this transition is very smooth. NARRATOR: Leonardo's techniques are still taught today in his hometown of Florence. To bring his paintings to life, artists strive to capture human flesh and the way light reveals its form.

CECIL: Leonardo talks about the smoky transition from light to shadow. This is how we perceive in nature. The problem we often see with photographic images is that there is so much detail that we don't get the fullest effect. We see life very out of focus: we look. NARRATOR: Other artists of the time, such as Sandro Botticelli, painted figures with hard contours. But Leonardo used the thin layers of it to create smooth transitions, darkening the lines. This is his characteristic appearance, called "sfumato", from the Italian "fumo" or smoke. Without a doubt, the most famous example of Leonardo's sfumato is that enigmatic smile of the "Mona Lisa." DELIEUVIN: Just look at the mouth.

Look at the eyes. You can't see the lines. You simply see the movement of light. That is incredible and there is no comparison with other artists of that era. KEMP: There's no advantage there. It's all very uncertain. Of course, this plays a psychological role, because she is present but somehow not tangible. It is idealized. NARRATOR: For Leonardo, sfumato captured in two dimensions what he observed in the three-dimensional world. But to get the perfect skin, he had to go deeper: get to the muscles and tendons underneath. Keep it like this. NARRATOR: Trudy Van Houten has taught anatomy for 30 years.

Perfect. VAN HOUTEN: Leonardo da Vinci constantly inspires me. NARRATOR: She says the science of anatomy is beautiful. SYLVAIN: Do you want me to cut that? VAN HOUTEN: Yes, please. NARRATOR: Although the process often is not. VAN HOUTEN: Good. You have beautifully preserved that little container. NARRATOR: Leonardo dissected 30 bodies. And without refrigeration it would have been especially unpleasant. The intestines would have been a particular problem because they contain many bacteria. And even after death, the intestines swell and become larger and larger. That's where things were going to go wrong the fastest and smell the worst. It is a very complicated matter.

NARRATOR: Many of the drawings from Leonardo's messy dissections live today in the finest of places: Windsor Castle, just outside London. Steps from where Prince Harry and Meghan Markle posed for their wedding photos, more than 200 Leonardo drawings are housed in the Print Room. Martin Clayton is the curator of those drawings. CLAYTON: He couldn't help but make a beautiful drawing. But what interested Leonardo most was the structure, the machinery of the body. And this particular drawing is one of the best examples of how Leonardo tries to understand how the shoulder works in purely mechanical terms. There is no mystery of the body.

The body is a machine that can be looked at and analyzed in purely objective terms. NARRATOR: The beauty of Leonardo's drawings is undeniable. But in light of everything we've learned with the help of tools like MRI, did it get it right? VAN HOUTEN: If I were asked to grade his anatomical drawings, they would go from A to F. His drawings of the muscles, of the things that he was directly observing and to which he gave functional meaning, I would give an A-plus. As for some of the organs, I couldn't do it. NARRATOR: One of Leonardo's most ambitious anatomical drawings is called the "Grand Lady." It's considered a masterpiece, but for Van Houten it's a bit of a mess.

VAN HOUTEN: The feature I immediately turned to is foreign structures flying out of the sides of the uterus. They reminded me of pointed carrots. CLAYTON: These strange type of horn-like structures are ligaments observed by Leonardo in a cow. Leonardo assumed that all mammals have the same structures. He is feeling his way into a field that has never been illustrated before. NARRATOR: Leonardo's in

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tive dissections certainly influenced his art. ♪ ♪ He returned to this painting, "Saint Jerome," after 20 years, revising the neck to accurately represent the muscle beneath it. He did not revisit one of his early paintings, "Ginevra de' Benci", and it shows in what has been called the flatness of his face.

But by the time of the "Mona Lisa," Leonardo's knowledge of anatomy is wonderfully con

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ng. An intriguing page from Leonardo's notebooks shows several illustrations of human lips in exaggerated expressions, made from dissections. ISAACSON: And it shows how every muscle and every nerve affects the lips, and at the top is this faint little sketch, and you see the first sketch of what will be the "Mona Lisa's" smile. NARRATOR: Anatomy and his painting technique partly explain how Leonardo infused the "Mona Lisa" with a realistic quality. But to complete the illusion, he needed to explore another area of ​​science: how humans see.

GALLUZZI: Come in.Among the many aspects in which Leonardo was using his knowledge as a scientist to become a better painter is optics. And Leonardo calls optics "perspective." FARGES: It's basic geometry, because when you have an object with parallel lines, they will appear to vanish at a point, which is called the vanishing point. NARRATOR: Leonardo was fascinated by many aspects of how we perceive our world. He even studied the composition of air to determine how the atmosphere affects the appearance of distant objects. Leonardo tries to capture the complexity of the world. But how can you paint something you can't see, like the transparency of air?

ISAACSON: Leonardo not only looked at the mathematical perspective, but he also looked at how colors change as you move away, how the sharpness of something changes as you move away from it. NARRATOR: And Leonardo also discovered tricks of perception to achieve the greatest illusion of all: that elusive smile? She is looking outside and her smile is a reaction caused by someone's arrival. This is the fiction that the painting attempts to establish. Great artists know how to attract you, but not tell you what to think. They offer the provocation. NARRATOR: The ambiguity of Mona Lisa's smile is actually part of her appeal.

How did Leonardo achieve this effect? That's a question that intrigued neurophysiologist Margaret Livingstone. She studies the human visual system: how our eyes and brain operate together to make sense of the world. LIVINGSTONE: As a neurophysiologist, I learn a lot from artists, because they study how we see. I study how we see. Much good art takes advantage of the brain's calculations by exaggerating things that the visual system considers important. NARRATOR: Human vision is among the best in the animal kingdom. The center of our retina is full of special photoreceptors that allow us to see details or sharpness.

But away from the center, towards the periphery, there are fewer such receivers. We can see movement, but no details. LIVINGSTONE: Okay, now I want you to close your eyes. I'm going to put two versions of the "Mona Lisa", one accurate and one distorted. NARRATOR: To illustrate, Livingstone recruits her colleague Peter to see if she can spot a fake "Mona Lisa" using only her peripheral vision. Well, she briefly opens her eyes and looks at the yellow spot, then closes them immediately. And I point out what the exact reproduction is. She opens her eyes and checks if you chose the right one. ♪ ♪ ♪ ♪ (laughs) LIVINGSTONE: Point to the real version. (laughs) Can I keep that? (Laughter) NARRATOR: Peter got only one of the four "Mona Lisas" right, and Livingstone says that's not unusual.

LIVINGSTONE: Most people don't know how bad peripheral vision is, because as soon as something happens in their peripheral vision, they look at it and then they bring in the high-resolution part of their visual system. NARRATOR: In fact, our eyes move constantly, three times a second, filling in the details. The effect got Livingstone thinking: Could this explain why the "Mona Lisa" sometimes appears to smile and other times not? Using a photography app, blur the image, like in our peripheral vision. LIVINGSTONE: So I filtered the image in such a way that it would look like what you would see in your peripheral vision, knowing what I know about processing.

NARRATOR: The result? LIVINGSTONE: She's smiling from ear to ear. NARRATOR: As you look at the "Mona Lisa," your eye moves around the painting. When you look away from her mouth, she enters your peripheral vision and Mona Lisa appears to smile. But if you look directly at her mouth, the smile fades. LIVINGSTONE: She looks like she's alive, because she looks different depending on where you look. ISAACSON: Leonardo's paintings come to life because he understands human emotions and because he has a good sense of the underlying science. That combination is combined year after year as he makes the "Mona Lisa" into an interactive painting. (people talking in background) (speaking French) NARRATOR: Back at the Louvre, Cinzia Pasquali has removed the old yellowish varnish from "Bacchus," revealing the brilliant original colors.

She reveals an atmospheric perspective that suggests Leonardo's touch. DELIEUVIN: By removing these layers of darkened and yellowish varnish, we were able to rediscover the original shapes, the quality of the blue. It is a wonderful blue. And see how the painter represents these cities with that effect of humidity, what Leonardo called atmospheric perspective. NARRATOR: But Pasquali's research has also uncovered details such as the heavy shading on her face, which does not show Leonardo's characteristic sfumato fingerprint. I can't see Leonardo's touch. This is a bit mechanical. This shadow line is very difficult, you know? Leonardo, don't do this.

NARRATOR: Pasquali and the Louvre team have solved a centuries-old mystery. The "Bacchus" cannot be attributed to Leonardo. ♪ ♪ But that doesn't mean he wasn't involved. Very often, his apprentices are the ones who paint the paintings, so he would conceive the general design of the work and then delegate the manual execution to members of his workshop. ♪ ♪ NARRATOR: The restoration has managed to restore much of the original beauty to this painting. But it also raises an intriguing question: Should the same be done for the "Mona Lisa"? DELIEUVIN: You have to imagine that under that varnish you could see a wonderful blue sky.

Your face or hand will probably also be pinker, like natural skin. ISAACSON: If we could remove that veneer, we could see it as Leonardo really did. But I think the French governments have fallen for less reasons than trying to take the "Mona Lisa" out of circulation and clean it up. NARRATOR: Maybe there is another way. Could you give it a digital makeover? That's what Pascal Cotte is trying to do. He has analyzed the "Mona Lisa" with an extraordinarily powerful camera and lights, which he demonstrates through a replica. (Device hum) COTTE: We make the measurements in the basement of the Louvre, inside the laboratory.

It is very emotional to have the painting in your hands without the frame. You can look at this painting under this very intense light, which reveals everything you can't normally see. ♪ ♪ NARRATOR: Cotte's extremely detailed scan of the "Mona Lisa" and his analysis of the paint's optics and chemistry reveal how the colors may have changed over time. It is not only the varnish that yellows and darkens, but also the pigments and oil in the paint itself. Cotte's challenge is to reverse engineer the effects of that aging. KEMP: It's not just about touching it up and altering the colors, which you and I could do and get tolerable results, but it's based on pigment analysis.

NARRATOR: First, Cotte determines how much the varnish has darkened and, using his computer, removes it. (Buzz) Next, he identifies what the color of each pigment would have looked like 500 years ago and recreates them to see the colors just as Leonardo did. COTTE: For example, we know that Leonardo made the sky with white lead and lapis lazuli. Therefore, we have software that removes incorrect colors to obtain the genuine color. NARRATOR: Then, pixel by pixel, Cotte restores those colors. Suddenly, a greenish sky turns bright blue and a bit of blush returns to Lisa's cheeks. Finally, as the French say: voilà.

KEMP: Suddenly, she doesn't look like an underwater goddess anymore. She looks like she's outdoors, which is fantastic. NARRATOR: Cotte's restoration has brought Lisa back to life, at least digitally, closer to the state Leonardo saw her in, allowing us all to see the legendary beauty of the painting and the science it required: the geometry and optics of the perspective; the anatomy behind her face; and the soft lines of sfumato, capturing the mystery and movement of life. But even with all modern knowledge, the "Mona Lisa" is much more than the sum of its scientific parts. Ultimately, pinning down exactly why we're so drawn to her remains as elusive as her smile.

NARRATOR: Three years before his death, Leonardo was invited to France to live and work for the king. He crossed the Alps on horseback or mule, carrying three paintings. Those paintings, including the "Mona Lisa," now hang in the Louvre, where the doors are about to open on the blockbuster 500 Years of Leonardo exhibition, a celebration of a genius who merged the worlds of art and science. DELIEUVIN: Leonardo is an Italian Renaissance painter, but his genius is universal and he speaks to everyone. ♪ ♪ BORGO: Leonardo wanted you to forget that you are looking at pigments on a piece of wood.

The idea is that you are looking at a living, breathing being. ♪ ♪ ISAACSON: The key to Leonardo da Vinci is that he makes no distinction between the beauty of nature that he studies in his science and the beauty of his art. ♪ ♪ he could have spent more time just being a painter. But if he had done that, he would not have been Leonardo da Vinci and he would not have painted the "Mona Lisa." ♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪