* Michelangelo finished Pieta statue in 1500
* Attack in May 1972 left more than 100 fragments
* Restoration took 10 months, now behind bullet-proof glass
By Philip Pullella
VATICAN CITY, May 21 (Reuters) - Forty-one years ago, a crazed Hungarian named Laszlo Toth jumped an altar railing in St. Peter's Basilica and dealt 12 hammer blows to Michelangelo's Pieta, severely damaging the Renaissance masterpiece.
To mark the attack on May 21, 1972, the Vatican Museums held a day-long seminar on Tuesday on the statue, the incident, and what subsequently became one of the most delicate and controversial art restorations in history.
In his attack on the statue, which depicts the Madonna holding the body of the dead Jesus minutes after he was taken down from the cross, the unemployed geologist knocked off her left arm and hand.
Toth, who alternately said he was Jesus Christ or Michelangelo, also broke her nose in three parts and left about 100 other fragments, including chips from the back of her head, lying on the floor of the chapel where it was on display.
At the time, art historians were divided on how to proceed with the restoration of the masterpiece.
The statue is so lifelike that a viewer can almost feel the curls of the dead Christ's hair and the softness of the Madonna's lips.
The veins in Christ's muscular arms seem to be still holding blood. The folds in the Madonna's veil seem made of muslin rather than marble.
When art historian Giorgio Vasari saw the statue in 1550 he wrote in his book about the lives of artists.
"It is a miracle that a rock, which before was without form, can take on such perfection that even nature sometimes struggles to create in the flesh".
After the attack, some art historians and restorers wanted the statue to remain as it was damaged as a sign of the violent times. Others said it should be restored but with clear marks delineating the damaged parts as a historical testament.
The Vatican instead decided on what is known as an "integral restoration," one that would not leave any traces of the intervention visible to the naked eye.
"With any other statue, leaving the wounds (of the attack) visible, however painful, could have been tolerated," said Antonio Paolucci, director of the Vatican Museums.
"But not with the Pieta, not this miracle of art," he said.
Michelangelo was commissioned on August 27, 1498 and carved it out of a single block of Carrera marble he chose himself from a Tuscan quarry. The contract, with Michelangelo's signature, is preserved in the Vatican.
Nazzareno Gabrielli, the last surviving member of the team that restored the statue in 1972-1973, said there were "a lot of difficult moments in the debate as the plan of action was decided, some anxiety, and perplexities during experimentations in the laboratory".
Using previous photographs, it took more than five months to identify all the pieces and fragments, some the size of a fingernail, before starting to put them back together in a makeshift laboratory built around the statue in the chapel so it would not have to be moved.
"It's a good thing the hammer blows were vertical. If they had been horizontal he could have knocked the head right off," one of the restorers says in a documentary screened at Tuesday's seminar.
Using a specially made invisible glue and powder made from the same type of marble, the restorers painstakingly pieced together the chunks and fragments, including one that arrived anonymously from the United States.
A tourist who was in the basilica picked up a piece in the confusion as police were arresting Toth. The tourist later apparently felt guilty and mailed it back.
One of the most precious discoveries was the Madonna's eyelid.
The gaps left after all the fragments were in place were filled with replacement pieces made from a copy of statue that had been made from a mould before the attack.
Some 10 months after the attack, the Pieta went on display again in the chapel that bears its name, this time behind a panel of bulletproof glass, where it is viewed by millions of people a year. (Reporting By Philip Pullella)