A robot based on drawings by Leonardo da Vinci

Photo: Model of a robot based on the drawings by Leonardo da Vinci; photo by Erik Möller, Genie exhibit, Berlin 2005.

Leonardo da Vinci was respected as an engineer, during his lifetime. When he fled to Venice in 1499 he was employed as an engineer and devised a system of moveable barricades to protect Venice city from attacks. He kept detailed notes and sketches of his scientific ideas. His journals include a vast number of notes on inventions, some of which are practical and others found to be impractical. He did not take much pain to conduct experiments or prove scientifically about scientific ideas he noted in his journals. They include musical instruments, hydraulic pumps, crank mechanisms, mortar shells, bridges, flying machines (a helicopter and a light hang glider), mills, levers, hoists, winches, pulleys, gears, lens-grinding machine, hydraulics, war machines, cannons, diving suit, and many more.

What’s the secret behind Mona Lisa's enigmatic smile?

Art critics, art enthusiasts, experts on paintings, especially those who spend considering amount of time in studying the hidden secrets of da Vinci creations, always wondered about one of the charms of the world's most famous painting, Mona Lisa: she appears smiling one moment and then becomes serious and sardonic the next moment. While one viewer will feel her radiant, the other will perceive her mood as something different. It is rather mysterious, most people have always felt.

But in October 2009, scientific research offered an explanation to Mona Lisa’s changing moods, “Our eyes send mixed signals to the brain”. The scientists proved that Mona Lisa's smile depends on which cells in the eye’s retina pick up the image and which channel the image is transmitted through in the brain. To make it clearer, when one channel wins over the other you see the smile, sometimes other channels take over and you do not see the smile.

It is well-known that different cells in the eye are designed to pick up different colors, contrasts, backgrounds and foregrounds. Some eye cells deal with central vision while others with peripheral vision. So, what cells pick up the image first depends on what channel they are sent to the brain for interpreting the image. These channels decode the data about an object's size, clarity, brightness, distance and location in our visual field.

"Sometimes one channel wins over the other, and you see the smile, sometimes others take over and you don't see the smile," said Dr Luis Martinez Otero, a neuroscientist at the Institute of Neuroscience in Alicante, Spain, who conducted the study, the New Scientist had reported.

To get a clear idea of the reasons behind Mona Lisa's vanishing smile, Dr Martinez Otero changed various aspects of Mona Lisa that are processed by different visual channels, and then asked the volunteers whether they saw a smile or not. Next, the volunteers were asked to look at Mona Lisa in different sizes from varying distances. Based on the volunteers’ responses, they found the closer you were to the painting, the more likely you could see Mona Lisa’s smile.

Dr Martinez Otero's team also compared how light affects our judgment of Mona Lisa's smile. Two kinds of cells determine the brightness of an object relative to its surroundings, ‘on-centre’ cells which are stimulated only when their centers are illuminated and allow us to see a bright star in a dark night, and ‘off-centre’ cells which turn on only when their centers are dark, and help us to pick out words on a printed page.

Dr Martinez Otero jammed these channels by showing either a black or white screen for 30 seconds, followed by a picture of Mona Lisa. The experiment showed that black would mute ‘off-centre’ cells while the while affects ‘on-centre’ cells. It indicated the volunteers were more likely to see Mona Lisa's smile after they had been shown the dark screen, making Martinez Otero to conclude that it is these ‘on-centre’ cells that sense Mona Lisa's smile.

Eye gaze also affects how volunteers see the smile, according to Dr. Martinez Otero, whose team used software to track where in the painting the 20 volunteers gazed while they rated whether or not Mona Lisa's smile became visible or not. With one full minute to gaze at the painting, the volunteers tended to focus on the left side of her mouth when they judged her as smiling. It was further evidence that off-centre vision picks out Mona Lisa’s smile. When the volunteers had only a fraction of a second to discern her smile, their eyes tended to focus on her left cheek, showing that peripheral vision plays a role too.

Now the question is: did Leonardo da Vinci intend to create so much confusion in the brains of viewers? Yes, absolutely, Martinez Otero contends, "He wrote in one of his notebooks that he was trying to paint dynamic expressions because that's what he saw in the street." After all, Leonardo da Vinci was no ordinary painter or genius. Leonardo was the rare archetype of the Renaissance man, an extraordinary genius whose unquenchable curiosity was equaled only by his powers of invention. And his range of expertise and professions spanned a wide range of subjects, as he was renowned as a painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist, writer, and many more.

Leonardo's studies in science and engineering were as innovative as his artistic work, recorded in notebooks comprising some 13,000 pages of notes and drawings, which fused art and natural philosophy, which was the forerunner of modern science. Interestingly, Leonardo wrote with his left hand, and his notes were mostly written in mirror-image cursive handwriting, which has led many people to speculate that he did so for reasons of secrecy.

Dr Luis Martinez Otero’s research finding on the mystery of the smile of Mona Lisa was originally presented at the Society for Neuroscience's annual meeting in Chicago.

This is not the first time scientists have deconstructed Leonardo da Vinci's masterpiece, Mona Lisa. In 2000, Margaret Livingstone, a neuroscientist at Harvard Medical School with a side interest in art history, showed that Mona Lisa's smile is more apparent in peripheral vision than in dead-centre vision.

Perhaps, no other artist’s works underwent the scrutiny of scientists and investigators looking for mysteries and hidden secrets as in da Vinci’s works. Another of his magnum opus that has intrigued scientists, investigators and others including the best selling author Dan Brown is The Last Supper, based on which Brown built up the plot of The da Vinci Code, which was made into a blockbuster movie.

The Last Supper by Leonardo da Vinci

During the Passover festival Jesus Christ came with his followers to Jerusalem where a large crowd came to meet him. Jesus cleansed the Herod's Temple by overturning the tables of the moneychangers who set up shop there. Following this, Jesus celebrated the Passover meal, the last meal Jesus shared with his disciples before his death. It is an event that was later known as The Last Supper, in which he prophesied that he would be betrayed by one of his disciples and he would then be executed. In this ritual supper, Jesus took bread and wine in hand saying, ‘This is my body which is given for you’ and ‘this cup which is poured out for you is the New Covenant in my blood’, and instructed them to ‘do this in remembrance of me’ (Luke 22:7-20).

In The Last Supper, Jesus washes his disciples' feet and gives his farewell discourses, discussing the persecution of his followers, the coming of the Holy Spirit, etc. He says a long final prayer with his disciples before heading to a garden where he knows Judas will show up.

According to the Synoptic Gospels, Jesus institutes a new covenant of his blood and body, the wine and bread. Some Christians describe this as the ‘Institution of the Eucharist’. Others view the Last Supper as later derived from first century Eucharistic practice.

The vessel which was used to serve the wine is sometimes called the Holy Chalice, and has been one of the supposed subjects of Holy Grail literature in Christian mythology. Also The Last Supper has been the subject of many literary works and paintings, of which the painting, The Last Supper, by Leonardo da Vinci is perhaps the best known.

Mona Lisa: restored version

Mona Lisa: retouched picture

This is a retouched picture; digitally altered from its original version to modify color and remove yellowing.

Mona Lisa: Portrait of Lisa Gherardini, wife of Francesco del Giocondo

Mona Lisa (La Gioconda or La Joconde), a sixteen-century portrait painted in oil on a poplar panel in Florence, Italy by Leonardo da Vinci, is owned by the Government of France and is on display at the Louvre museum in Paris under the title Portrait of Lisa Gherardini, wife of Francesco del Giocondo.

Described by art-lovers as the most famous and iconic painting in the world, Mona Lisa was in obscurity until the mid-nineteenth century when artists of the Symbolist movement began to appreciate it and associated it with ideas of feminine mystique. Walter Pater, in his 1867 essay expressed this view by describing ‘the figure in the painting as a kind of mythic embodiment of eternal femininity’, who is ‘older than the rocks among which she sits’ and who ‘has been dead many times and learned the secrets of the grave.’

Leonardo Da Vinci began painting Mona Lisa in 1503, lingered over it four years and left it unfinished. He continued to work on it for three years after he moved to France and finished it shortly before he died in 1519. He took the painting from Italy to France in 1516 when King François I invited him to work at the Clos Lucé near the king's castle in Amboise. Then, most likely, through the heirs of Leonardo's assistant Salai, the king bought the painting for 4,000 écus and kept it at Château Fontainebleau, where it remained until given to Louis XIV, who moved the painting to the Palace of Versailles. After the French Revolution, it was moved to the Louvre. Napoleon I had it moved to his bedroom in the Tuileries Palace and returned it later to the Louvre. During the Franco-Prussian War (1870-1871) it was moved from the Louvre to a hiding place elsewhere in France.

Salai as John the Baptist

Painting: Salai as John the Baptist (1514), Louvre

For the painting of John the Baptist, Leonardo da Vinci used his pupil Gian Giacomo Caprotti da Oreno, nicknamed Salai, as a model. Salai entered Leonardo's household in 1490, in a year, Leonardo made a list of his misdemeanors (a thief, a liar, stubborn, and a glutton) after he had made off with money and valuables on at least five occasions and spent a fortune on clothes. Still, Leonardo treated him with great indulgence and Salai lived in his house for the next thirty years. Salai executed a number of paintings under the name of Andrea Salai.

Casa Leonardo, the house where Leonardo da Vinci grew up

Photo: Casa Leonardo, the house where Leonardo da Vinci is believed to have grown up. It is situated alongside Via di Anchiano, 3km north of Vinci, Tuscany, Italy.

Leonardo da Vinci (1452-1519), the Italian painter, sculptor, architect, cartographer, anatomist, musician, scientist, mathematician, engineer, inventor, geologist, botanist and writer, was born on April 15, 1452, in the Tuscan hill town of Vinci in Florence. He was the illegitimate son of Messer Piero Fruosino di Antonio da Vinci, a Florentine legal notary, and Caterina, a peasant woman. It is believed Leonardo spent his first five years in the hamlet of Anchiano in the home of his mother, which is shown in the above photo.