Notes:

"But this Guarnerius violin was the prized possession of Jascha Heifetz, generally considered the best violinist of the 20th century. It has been played only occasionally since 1987, when Heifetz died and the instrument was bequeathed to the Fine Arts Museums of San Francisco.

Under an agreement struck this summer, Barantschik will get to play the Guarnerius often over the next three seasons. Months after the announcement, Barantschik still can't believe his eyes -- or his ears.

"When I look at it, it's striking," said Barantschik, entering his second season as conductor Michael Tilson Thomas' top violinist. "You can't avoid thinking about people who have touched it and what they played and how they played.

"The complexity of the sound is different from anything else I've tried in my life. It has a dramatic, dark sound. It's very inspiring."

How the violin landed in Barantschik's lap is a story of craftsmanship, luck, collaboration and two baffling questions that remain unanswered.

The first mystery is how the Guarneri and Stradivari families managed to build instruments that, nearly three centuries later, are the preferred brands of the world's top violinists. After all, how many other devices made in 1742 are considered superior in 2002?

"There are many theories about it, but nobody knows exactly," Barantschik said of the Guarnerius secret. The type of wood is an obvious possibility, but no one is certain.

His model is one of about 130 remaining built by Giuseppe Guarneri of Cremona, Italy. He's also known as "del Gesu" because he added the Greek abbreviation for Jesus to his labels.

Del Gesu was merely continuing the family tradition of violin making, and it wasn't until the 19th century that Guarnerius instruments became popular, according to Joseph Grubaugh, a well-respected violin maker and restorer in Petaluma.

"This is not to say that we don't think of him as a genius, but I'm sure he didn't consider himself breaking new ground, Grubaugh said. "Gesus were probably first discovered maybe around 1810, where people started bringing them out of Italy, saying, `Wow!'

The same instrument Barantschik plays this week was used by German violinist Ferdinand David, who used it for the world premiere of Felix Mendelssohn's Violin Concerto in 1845. So the violin picked up a nickname: "The David."

Heifetz bought "The David" in 1922. He played it in nearly all of his concerts and recordings.

When Heifetz died, the second great mystery surrounding "The David" was uncovered.

In his will, Heifetz gave his prized violin to the De Young Museum in San Francisco. Nobody knows why.

"He had been in San Francisco in an important period of his life," said Fine Arts Museums director Harry S. Parker III, taking his best guess. "But there was nothing to indicate in his will why he would give it to an arts museum as opposed to a symphony or conservatory."

Heifetz also ordered in his will that the instrument be used "on special occasions by worthy performers."

Until this year, that meant "The David" was under glass except for the occasional performance by world-class artists or specially selected students of the San Francisco Conservatory.

Former San Jose Symphony violinist and Conservatory student Heidi Kim got her chance last year.

`Amazing experience'

"It's a pretty amazing experience," said Kim, of Mountain View, who like all students was watched by security guards the entire time. "The sound is so incredibly sweet. It really doesn't compare to anything else."

You can listen for yourself Wednesday, Thursday and at various other symphony concerts throughout the year. It's Barantschik's choice.

Under the agreement, he will play the violin in three chamber music concerts at the Legion of Honor in the spring. He said he will definitely use it when the orchestra makes its live recording of Gustav Mahler's Third Symphony later this month.

And when it's not being used, the violin will be under tight security.

San Francisco Symphony executive director Brent Assink, who helped broker the deal with the Fine Arts Museums, said: "We're taking all the necessary precautions that one would take."

Just like you would for any standard $6 million loaner."

Heifetz Violin, Fine Arts Museums of San Francisco