FERRARA - Extraordinary discoveries are sometimes a matter of millimeters -- and years of research.

When the Italian architect Claudio Sgarbi set his ruler along a drawing of an obscure Renaissance manuscript, he was suddenly struck by what he found. He quickly compared it to a copy of the Latin author Vitruvius' De Architectura (On Architecture), which featured a drawing of a man with arms wide apart, inscribed in a circle and a square. His navel was at the center of the circle, and his genitals were at center of the square.

"Among the several graphic interpretations of the human body's proportions that were theorized by Vitruvius, we are aware of just one other with the same geometrical features," Sgarbi says. "It is the one by Leonardo Da Vinci."

For more than 30 years, Sgarbi – a historian of architecture - has studied the manuscript he discovered by chance in the Ariostea Library in Ferrara, in northern Italy. He wrote an essay on the second Vitruvian man that is set to be published, and is working on a book about its story. The American journalist Toby Lester wrote about Sgarbi's discovery in a chapter of his book Da Vinci's Ghost.

Leonardo's Vitruvian man is the most famous anatomical drawing in history, in itself considered by some to be the depiction of Humanism. The man of the manuscript from Ariostea Library looks very different, and is by no means a great master's work of art. Still, its measurements are the same.

Up until now, Leonardo was believed to be the first to have found geometrical solutions to the Latin theoretician's indications. "At the beginning, I thought that it was a later drawing, inspired by Leonardo's," Sgarbi recalls. "Then, I measured the half-erased borders of a larger drawing. It was the same man, still inside a circle and a square. The final drawing had been reduced by half."

Sgarbi explains that the erased drawing has a side of the square that measures 180 millimeters, with the circle's radius of 108 millimeters, which are the same dimensions of the square and the circle of Leonardo's drawing, housed today in Venice's Gallerie dell'Accademia.

The main difference with Leonardo's drawing are signs of several changes. "Above all, the erased part overlaps with the borders of the manuscript. This leads us to think that it came before Leonardo's drawing, which is assumed to date between 1490 and 1500," says Sgarbi. "It is hard to imagine that the author of the manuscript from Ferrara chose a piece of paper of the same size of Leonardo's drawing. The opposite makes more sense. Indeed, Leonardo's piece of paper is larger than usual. It looks like he wanted to make space for a drawing of an unusually large size for a manuscript."

Mystery and pursuit

Not everyone agrees with this theory. "The geometry and the position of the arms are wrong," says Martin Kemp, Professor Emeritus of the History of Art at Oxford University, widely considered the world's leading authority on Leonardo. "The arms are angled upwards. If horizontal, they don't work anymore. Moreover, the head is not on the same line drawn by the extremities of the hands. The manuscript of Ferrara is very important, but I think that it dates after Leonardo's drawing."

Sgarbi instead believes the author of the drawing from Ferrara found a different solution, with the fingers touching the lower intersection of the circle and the square in one position. "Leonardo added a dynamic element. But there are many similarities between the two drawings," Sgarbi says.

The architect's theory sets off a historical and artistic mystery. Did Leonardo copy or get inspired by the Ferrara drawing? Why did this obscure "brother" remain unknown for centuries? Who is the mysterious author?

"I've never thought that Leonardo copied," explains Sgarbi. "Instead, I think that the definitive version of the Vitruvian man was a collaboration between some of the most brilliant minds of the Italian Renaissance."

During the Middle Ages, many artists had already tried to portray the man described by Vitruvius. He appeared in miniature paintings as a Christ on the cross, and later in a 1480 drawing by Francesco di Giorgio Martini. But they all failed in the effort to translate the geometry theorized by the Latin thinker.

Among Italian humanists, the quest for the Vitruvian man became the pursuit of symbolism. The circle represented God and the universe, and the square represented the Earth. The man had to be inscribed within these two figures.

"The Vitruvian man from Ferrara appears to be a step towards Leonardo's great solution," says Sgarbi. "The manuscript was unnoticed for so long due to a mistake in the cataloguing, which defined it as a partial transcription of the ten books of the essay. But in truth, here for the first time Vitruvius' work was fully studied and magnificently illustrated."

The Ferrara document shows some of the same technical solutions that Leonardo was working on, and some indeed see Leonardo's hand in it. Now Sgarbi thinks to have identified the author of the manuscript. "Many clues point to Giacomo Andrea da Ferrara, a scholar, architect and politician, who worked closely with Leonardo," he says.

In his letters, Leonardo wrote about "another Vitruvius'" owned by Giacomo Andrea. Today, there aren't many remaining accounts of Giacomo Andrea's life. We know that, as a supporter of Ludovico Sforza, he was put to death during the French occupation of Milan. He was executed by quartering, his arms and legs spread wide apart -- like a Vitruvian man. This omen might make for the perfect start for a new Da Vinci Code.

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