Maybe it was remnants of the Sept. 11 anniversary earlier this week.

Maybe it was the realization that while of course Paul Simon isn’t quitting music, this is surely, as he promises, his final tour.

Or maybe it was the unadorned beauty of the music, the tenor saxophone and violin that emanated from the darkened stage and gently swelled as Simon walked out and took a shy bow.

Whatever it was, the moment he uttered the first lines of “America,” Simon was quietly captivating and stirring, the first of many time capsule moments in his 2 ½-hour Atlanta goodbye.

»PHOTOS: See our gallery from Simon's Atlanta farewell

Playing at Cellairis Amphitheatre at Lakewood – a venue he requested to accommodate the nearly dozen musicians in his stellar band – Simon neither looked nor sounded his 76 years.

The high range has been buffed from his vocals, but he can still hold a long note, as he did during “The Boy in the Bubble,” his slight shoulders swaying and shrugging to the music.

In a plum T-shirt and snazzy black jacket – shed after a few songs on this oppressively muggy night – Simon elicited a roar from the crowd as he rolled his hands in the air and yes, danced during “That Was Your Mother,” which might also mark the first time an artist has played air washboard on stage.

Paul Simon spoke warmly to the crowd throughout the 2 1/2-hour concert. Photo: Robb Cohen/ Robb Cohen Photography & Video /www.RobbsPhotos.com
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It was a show that regularly swung from contemplative to joyful, from simple guitar chords to labyrinthine rhythms and layered arrangements, perfectly encapsulating Simon’s illustrious career (also a worthy summary, Robert Hilburn’s excellent biography, “Paul Simon: The Life”).

An early highlight was the double percussive punch of “Mother and Child Reunion” and “Me and Julio Down by the Schoolyard,” steered by a quartet of sterling brass and a fully immersed Simon.

With the end of the “Homeward Bound” tour looming – it’s a wrap next week with three shows in his native New York– a guy as sensitive and perceptive as Simon is surely cognizant of the tick tock.

He spoke often, warmly and wittily to the crowd, which packed the covered section of the amphitheatre and filled pockets of the lawn.

A mention of “the songs Artie and I used to sing,” inspired cheers at the reference to erstwhile partner Art Garfunkel and the amusing backstory to “Rene and Georgette Magritte With Their Dog After the War” would have been worth hearing even if it hadn’t been followed by a gorgeous rendition of the song, with a six-piece string and horn section ringing Simon in a semi-circle.

The pared down section of the band also dazzled on “Can’t Run But,” the “Rhythm of the Saints” track reworked with locomotive cello and violins on his current “In the Blue Light” album.

While a few newer songs popped up in the set – the wry “Wristband” and “Questions for the Angels” among them – Simon kept the focus on a catalog that is one of the most tremendous in pop music history.

His rendition of “Bridge Over Troubled Water,” which he introduced by explaining his “strange relationship with” the song, teemed with mournful trumpet and gentle percussion that surged into triumphant hope coated with gospel fervor.

Paul Simon will wrap his goodbye tour on Sept. 22 in his hometown of Queens, New York. Photo: Robb Cohen/ Robb Cohen Photography & Video /www.RobbsPhotos.com
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His potent rhythm section uncorked congas, cowbells and cymbals for the jaunty combo of “Diamonds on the Soles of Her Shoes” and “You Can Call Me Al,” one of the unlikeliest Top 40 hits ever and one of the few songs with an enticing bass break.

But the success of “Al” and the insinuating grooviness of “Late in the Evening” further prove not only Simon’s brilliance as a songwriter, but also his fearlessness and love of musical experimentation.

Maybe he really is “Still Crazy After All These Years,” as he eloquently sang during the first of two encores.

“It’s been a long and great trip for me,” he said from the stage. “I really don’t know what I’m gonna do (next). I will keep writing. But I thought it would be interesting just to stop and think a little. Maybe travel. See what it’s like to be on Earth.”

And who can begrudge him?

But Simon is clearly such a restless musician – a band as fine-tuned as this hardly needed conducting, but he instinctively guided them with a waving right hand behind his back several times during the concert – that one wonders how long until the first master class is booked.

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