Unlike some modern-day Leonardo da Vinci buffs, Ben Sweeney wasn’t lured by the lore romanticized in Dan Brown's best-selling novel.  It was da Vinci’s “sinister” left hand that reeled him in.  At least, that's what the Carlsbad real estate broker thought he overheard while strolling through the Uffizi Gallery in Florence, Italy, eight years ago. A tour guide used the term il sinistra in reference to the 15th-century artist and inventor. Applying a literal translation of the word sinistra, another man in the group concluded that da Vinci must have had a deformed hand.  Sweeney returned to Carlsbad thus convinced, not realizing that the guide was most likely saying that the painter is thought to have been left-handed. (In Italian, mano sinistra, means left hand. The term sinister evolved from the once-common belief that left-handedness was an evil trait.)

Sweeney began to amass a collection of rare books containing reproductions of da Vinci's paintings, sketches and drawings. Having excelled in math as a student, Sweeney also was fascinated by da Vinci's mathematical formulas.
“I had to travel to different places to get access to his notes, and it was getting to be a real pain,” said Sweeney, 43.

The code in the codex
In 2002, Sweeney purchased a reproduction of da Vinci's Codex Atlanticus, a 12-volume, 300-pound collection of his drawings and notes on science, mechanics and biology.

Earlier this month, Sweeney displayed one of the hefty volumes in the library of the Prince of Peace Abbey in Oceanside, where his mother, Dolores, once found solace in the picturesque grounds. In 1999, the family dedicated a set of stained glass windows there in her name. Sweeney often visits to speak with the monks or to ruminate on his da Vinci studies.  “My mother would make the journey here daily and knew all the priests,” Sweeney said. “It's a very important place to me.”  The nearly 2,000 drawings in the Codex Atlanticus are first facsimiles reproduced by monks in Italy.

The volume Sweeney brought with him contains a red chalk sketch of da Vinci's so-called “weary hand” holding a stylus. Though art historians have long believed the oddly shaped hand to be indicative of a stroke da Vinci had late in life, Sweeney sees something different — fused third and fourth fingers, a trait characteristic of syndactyly, a condition in which two or more digits are joined together.

Sweeney believes a faint, broken line between the two fingers that appears to separate them is actually an imperfection in the paper.  “That's a syndactyly hand,” he said. “Historians had always seen photographs of this, but no one got to see the (original) red chalk drawing till these came out. Whenever they put it in books ... they just assumed there was a line here. They would draw what’s known as the interdigital crease to make it look more like a normal hand.”

ABC interviewed Sweeney recently about his theory for its series “Primetime: Medical Mysteries.” During the show, Dr. Joseph Upton, a Harvard clinical associate professor and hand surgeon, commented on the “crooked” ring finger in da Vinci's drawing. Though Sweeney's theory may never be proved, Upton said he believes the drawing appears to be that of a syndactyl hand.
Viewing a restored version of da Vinci's “The Last Supper” and an infrared color scan of “Madonna of the Yarnwinder,” Sweeney found what he believes to be clues concerning da Vinci's webbed hand.

In the restored version of “The Last Supper,” Christ appears to be gazing directly at his malformed left hand as he contemplates his fate.
“Leonardo understood the way you and I see things,” Sweeney said. “He knew the whole world, for 500 years, would walk by that hand and not call it the hand that it is.  “(da Vinci) said, ‘Someday I will do an illusion without trickery or mirrors.’ Nobody’s ever been able to figure out what he meant. This is that illusion.”  Under a surface layer of paint, Sweeney said, an infrared scan of “Madonna of the Yarnwinder” reveals the webbed hand of an infant Christ.
After viewing the scan, Upton wrote, “Unbelievable! This is what an uncorrected synpolydactyly looks like after the soft tissue separation.”
The surgeon showed Sweeney plaster casts made from hands of patients who have similar conditions as those displayed in da Vinci's works. Sweeney hopes to incorporate his research and some of Upton's 10,000 molds into a museum exhibit.

‘More than possible’
Dr. Robert Goldwyn, a clinical professor of surgery at Beth Israel Deaconess Medical Center in Boston, says Sweeney may be right about da Vinci's anomalous hand. Though Sweeney “may have the disadvantage of being outside the field of academia,” Goldwyn said, his lack of scholarly myopia may have allowed him to tap into something others have glossed over for 500 years.  “I think it's more than possible,” Goldwyn said. “The problem is that no one has looked at it that way before.” As further evidence, Sweeney points to da Vinci's early writings in which he refers to his left hand as la stanca mano, or his tired hand.  Goldwyn said the discovery could serve as an inspiration for people with physical challenges.  “Nobody has been like Leonardo with two hands,” Goldwyn said. “In the question of inspiring somebody it’s a tremendous leap.”

A personal quest
Sweeney graduated from Augustine High School in North Park, where he excelled at math. He later obtained a bachelor’s degree in finance from San Diego State University, with a minor in quantitative analysis.  His da Vinci inquiry isn’t limited to the artist’s left hand. In 2003, he purchased a robot built from da Vinci's sketches that he has loaned to museums around the country, including the San Diego Museum of Man. Sweeney also studies da Vinci's cartography, mathematics and botanical drawings.  “I never know what I'm going to work on from day to day,” Sweeney said. “One (project) is proving he had a telescope.”

Sweeney's father, Andrew, a retired engineer, serves as a sounding board for his exploration of da Vinci's math studies. He sister Dolores, a retired surgeon, has reviewed his hand research.  Another sister, Paula Brock, chief financial officer of the San Diego Zoological Society,   said the Sweeney family likes to serve as devil's advocates for one another. In regard to da Vinci’s hand, they’ve gone from incredulous to amazed, Brock said.

“We’re impressed with his focus, the scholarly level and the people with whom he has associated himself,” Brock said. “As time has elapsed, through the tangible analysis, we were mesmerized.”  Though Sweeney's family has been receptive to his ideas, some art historians have not.  “When I went to one expert ... he became agitated to think that Leonardo wasn't perfect,” Sweeney said. “I was like a little kid, all excited, and he said, ‘Leonardo’s the most beautiful man who ever lived. That's impossible.’”
Pat Sherman: (760) 752-6774