Fleck has risen to the challenge on this, his first Sony Classical recording. He's joined here by an eclectic selection of remarkable musicians: bassist Edgar Meyer, cellist Gary Hoffman, and violinist Joshua Bell, among others.

The joyous opening number, Scarlatti's “Sonata in C Major, K. 159,” features guest mandolinist Chris Thile of the hot new progressive bluegrass band Nickel Creek. Fleck's banjo and Thile's mandolin leap hand-in-hand through this musical pasture with gleeful abandon, the acciaccature of the mandolin in rollicking counterpoint to the banjo. The reoccurrence of the opening theme in the second half, rare in a Scarlatti sonata, is just a little more of a good thing.

This recording includes a half dozen of Bach's contrapuntal compositions. Originally intended as teaching pieces, the lovely inventions are almost like sorbet here, used to cleanse the palate between other works. Fleck's charming arrangement of the “Two-Part Invention No. 13,” with classical percussionist Evelyn Glennie on marimbas, breathes fresh air into this polyphonic work. The banjo's tinny crustacean progress is measured and deliberate against the deeply resonant floor of Glennie's marimba. Of the three Sinfonia on this CD, the shortest - the “Three-Part Invention No. 10” - is most interesting, with Thile on mandolin and Edgar Meyer adding an intricate bassline (and perhaps an audible breath or two).

Of the twenty works on this project, the two Beethoven offerings are the least successful. At just over nine minutes, the “Seven Variations on 'God Save The King'” is the longest cut on the album. Some of the variations work beautifully, while others slog and trudge through the melodic mud. “Moonlight Sonata,” which sometimes seems like classical music's version of “Foggy Mountain Breakdown,” simply does not work. Adding banjo to this somber piece almost makes a parody of it; one expects at any moment to hear a kazoo, a slide whistle, or the loud BANG! of a starter's pistol, à la Spike Jones.

However, most of the other arrangements on Perpetual Motion appropriately showcase Fleck's instrument of choice. The excerpt from Debussy's Children's Corner is stunning, with the contrast of the banjo crisp and honest against the soulfulness of cello and violin. A pair of Bach preludes (one from a partita for solo violin, the other from a suite for unaccompanied cello) proves that in the hands of a master, the humble five-string banjo can be a viable medium for this genre. The two mazurkas from Chopin are excellent, with Joshua Bell's Tom Taylor Stradivarius helping to extract all the melancholy drama from “Op. 6, No. 1.”

As Fleck mentions in his liner notes, this album was a physical challenge. He relied several times on a massage therapist to work on his arms, particularly as he was practicing and recording “Moto Perpetuo,” the piece for which this album was named. With Edgar Meyer contributing the lively piano accompaniment, Fleck moves through Paganini's virtuoso valentine at breakneck speed, and although the timing drags a tiny bit at about 2:35, it's still an impressive interpretation. The whimsical bluegrass version of this piece, with Bryan Sutton (former guitarist with Ricky Skaggs' Kentucky Thunder) is fun, though the guitar's role is much stronger here than the piano's on the classical offering, and the timing is compromised as a result.

To paraphrase Franz Lizst, as astonished by Paganini's brilliance in 1831 as listeners are by Fleck's banjo artistry, 170 years later: What a man! What an artist! What sufferings, what misery, what torture in those five strings! After interviewing him, I was left with an indelible image of Fleck with his ear pressed against an oak tree, listening for its faint, peculiar rhythms as he transcribed them for banjo. It almost doesn't matter what's set in front of this guy. Somehow, no matter how long it takes or how much it hurts, he'll figure out how to make it sound good on that five-string. Let's hope his massage therapist continues to rub him the right way.