At its core, Vermont jam band Phish is a fascinating blend of dichotomies -  serious and silly, focused yet erratic, sublime while stumbling -  all of which adds to the don't-you-dare-miss-a-single-show mentality that pervades its fan base. Phish-heads turn out in droves wherever the band schedules dates because they know that somewhere in the midst of those dichotomies will be one (or many) shining moments that will keep them coming back, again and again.

Yet, on Sunday, the final day of the band's Festival 8 at the Empire Polo Club in Indio, all sides of Phish were on display for the estimated 40,000 attendees.

EXHIBIT A: THE ACOUSTIC SET

The day began with Phish's first all-acoustic set since back-to-back nights at Neil Young's Bridge School Benefit in 1998. While coffee and figure-8-shaped donuts were distributed, the band members took their (unusual) places -  on opposite sides of the stage than normal, with a smaller kit for drummer Jon Fishman, a lone grand piano instead of the arsenal of keyboards employed by Page McConnell and a stool apiece for bassist Mike Gordon and guitarist Trey Anastasio.

Early in the 90-minute set, Anastasio suggested the audience sit instead of stand, as the band would be "playing a bunch of mellow songs." Eager to please their shaggy, bespectacled icon, the majority of fans did just that for the better part of the set. While the gesture was one of respect for the band and its music, it contributed to a chatty crowd; that usually isn't a problem during an electric Phish performance, but on Sunday morning it proved an unfortunate distraction.

Loquaciousness aside, Phish's selections walked the line between the safe and standard ("Water in the Sky," "Driver") and the more adventurous and rearranged ("The Curtain With," "McGrupp and the Watchful Hosemasters"). The latter two shone as examples of what Phish can do when the band members put their noses to the proverbial grindstone and actually practice (another stellar example being the previous night's front-to-back cover of the Rolling Stones' Exile on Main St.).

Towards the end of the acoustic set, Anastasio chopped out the four-note intro to "Wilson," and as the audience chanted back, he and Gordon leapt to their feet (with the crowd following instantly thereafter) -  and the sit-down portion of the show was officially over. Anastasio even apologized mid-song for asking everyone to take a seat, confessing that his own attention-deficit personality makes it hard for him to sit still. If that doesn't scream dichotomy, nothing does.

EXHIBIT B: THE SECOND SET

After a nearly three-hour break, Phish returned to the stage for an 80-minute electric set marked by a number of its more challenging songs, ones with odd time signatures, stop-on-a-dime changes and complicated arrangements. With the exception of a relatively rare Fishman flub halfway through the rigid-then-relaxed "Reba," Phish mostly nailed the rickety twists and turns of "Rift" and the swinging, fugue-like portions of "Guelah Papyrus" (all songs written in the first decade of the band's existence).

How do these examples fit the binary nature of the band?

Well, to be fair, they're not the most complicated songs Phish has written -  "Divided Sky" and "Fluffhead" both made well-executed appearances on Saturday -  but they're excellent examples of tunes that the band shied away from in its "post-hiatus" years of 2002-04, avoided mostly because the daily practice-practice-practice mentality that earned Phish its stripes early on seemed to fall by the wayside during those years.

Ever since Phish's return to touring this past March, there's a distinct focus on nailing many of these difficult compositions, as though the band members fully understand that they indeed have something to prove. This take-no-prisoners approach is vastly different (at least on the surface) than the happy-go-lucky young guns who rose to the jam band promontory in the '90s.

EXHIBIT C: THE FINAL SET

Beginning with the syncopated throaty funk of "Tweezer" and finishing with the ascendant peak of "Slave to the Traffic Light," Phish fired on nearly all cylinders during its concluding set. Here, the dichotomy lay in the vastly differing styles of songs that comprised the nearly two-hour finale, as the band moved from the aquatic, slip-sliding "Free" through the oddly timed polyrhythms of "Sugar Shack" and "Limb by Limb" to the disco-tinged delight of their cover of Deodato's "2001" theme.

The highlight of the set (perhaps the day, perhaps the whole weekend) was the late-set arrival of "Light," a cathartic epistle in which the band claims "the light is growing brighter now" and begs to "guide us to our goal / purify our souls." On the recently released Joy, "Light" begins with 80 seconds of plush ambience before storming through another three-minutes-plus of straight-ahead rock `n' roll. On Sunday night, Phish reversed the formula: Anastasio strummed the opening chords to "Light" as the closing cacophony of "2001" died out; here, the space opened up after the main thrust of the song ended.

As McConnell moved from piano to organ to synthesizer, and the jam out of "Light" grew heavier and spacier, a towering wall of diode-carrying balloons arose from the side of the stage, fluttering in flashy hues of blue, orange and pink. Eventually, the jam folded in upon itself just as fluidly as the balloon structure eventually sank back to earth, accompanied by washes of synthesizer, beating toms and volume swells.

This bizarre blend of scintillating arena-rock and gutsy atmospheric turbulence serves as a pronounced example of the new Phish, its latent dichotomous nature, and how the band best serves its two halves just as those halves serve the band. Like the set-closing "Slave to the Traffic Light," it's a ponderous lesson in group dynamics. Hearing loud and rowdy give way to gentle and delicate (or the other way around), seeing all smiles even when someone flubs a particularly difficult change, or feeling the way through a kinda-first-time outing on acoustic instruments, it's all what makes Phish's shining moments easier to find than miss.