Stradivarius violins — made in the 17th and 18th centuries — are regarded as the king of all instruments. They are so revered as to have become sacred: not for this time, but for the ages. One does not own a Stradivarius, one merely borrows one.

"It is on loan to me from the Stradivari Society of Chicago," said concert violinist Vadim Gluzman. "It's been on loan to me for 16 years now."

Gluzman will perform Pyotr Tchaikovsky's Violin Concerto -- with the Philadelphia Orchestra Thursday and Friday -- on the "Auer" Stradivarius made in 1690. Its most important owner was Leopold Auer, the Hungarian violinist for whom Tchaikovsky wrote the Violin Concerto in 1878.

Gluzman will play the music on the very instrument for which it was intended.

"There are certain sonorities in Tchaikovsky's writing that are very natural for this fiddle," said Gluzman after a rehearsal at the Kimmel Center. "I assume — I know Tchaikovsky heard Auer play — he was the fiddler in Russia at the time. So he must have had this sound in mind, in his ear, when he wrote this concerto."

However, Auer did not like the Violin Concerto, calling it "unplayable" and "un-violin-istic." He would not play its premiere. (Later in life, he did come around to the music, with edits.)

Nevertheless, Gluzman feels Tchaivoksky's music rests easily on the instrument. That's due, in part, to the subtle construction of the instrument and from the absorption of thousands of hours of play by masters," he said.

"Many ... will think I am out of my mind. Which is fine, because it's probably true," he said. "I think this thing is alive, and it has a soul. We leave imprints. We leave our stamps. Whether I want it or not, it's coming out."

Naysayers may dismiss Gluzman's remarks as mere psycho-acoustics. While it's true music is made of dedication and craft, the fact that this 320-year-old violin is coming full circle to the composition written for it leaves our subjective passions with something to chew on.