In 1964, Bob Dylan sang “Come gather ’round people / Wherever you roam” and people listened. Forty years later they’re still flocking: It took mere hours for his Harvard concert this Sunday, Nov. 21 to sell out. For the show, the Boston Fire Department will allow the Gordon Athletic Center, which usually only fits 1,500 people, to be filled with 3,500.

Generations come together at Dylan concerts, and this Sunday will be no exception. Yale kids, Harvard kids, Harvard faculty and staff, 500 lucky members of the public and a few readers will eagerly gather ’round the musical monument and his traveling band.

That Dylan is still selling out concerts four decades after his self-titled debut — at the notably fair price of $25 to 50, no less — is very telling. He has had unquestionable and persistent influence over the scope of American cultural understanding (ignoring a failed self-reinvention as a born-again Christian and musical missteps in the ’80s).

But he is perhaps best known as the reluctant figurehead for the political and social landscape of the ’60s. On albums like “The Freewheelin’ Bob Dylan” (1963) and “Highway 61 Revisted” (1965), Dylan proved that great music could be introspective but funny, culturally aware but told with stream-of-consciousness. It is because of him that great singers don’t have to have conventionally good voices, that folk music’s boundaries have become expandable, that public personas can be amorphous, and that idealistic unrest finds catharsis in music.

Since 1988, Dylan has been on “The Never Ending Tour,” a series of off-and-on performances that has kept him playing over 100 nights a year. To the dismay of fans, or at least those who only own his “Greatest Hits,” he stays clear of nostalgia, instead reshaping the his songs in concert. Though the near-constant revamping of songs allows for a new appreciation of his music and his musical process, it has sometimes forced his songs into uncomfortable contexts. At least he is still creative: especially because he rarely plays the same set twice, Sunday’s concert will be an original experience.

Dylan’s live show has changed recently. His voice has become withered, and he has been said to even perform songs without singing vocals — or perform whole shows without talking to the audience, a revelation surprisingly difficult to accept. Perhaps the most surprising aspect of his recent tour, especially to those expecting a troubadour and an acoustic guitar, is the music’s sheer loudness.

His recent endeavors outside of music are even more eccentric. Earlier this year, Dylan appeared as a leering and creepy voyeur in a Victoria Secret commercial, which used “Love Sick” from his 1997 masterpiece “Time Out of Mind.” The endorsement, his first ever, was remarkably appropriate for an artist who said when he was 24 that if he ever sold-out, if would be for “ladies’ undergarments.” Dylan may be multi-faceted, but no one has ever thought he was very sexy. Maybe this is another side of Bob Dylan that is best forgotten.

Earlier this fall, Dylan tried to give his fans insight into his mysterious life with his memoir “Chronicles: Volume One,” focusing especially on periods when he was on verge of life-altering epiphanies. Though he maintains his intense privacy about love and marriage, he delves into a handful of fascinating periods — his early years in New York before he began recording; his self-imposed exile in Woodstock, N.Y. after a motorcycle accident, and his late ’80s malaise.

“I’d come from a long ways off and had started a long ways down,” he writes of his start. “Destiny was about to manifest itself. I felt like it was looking right at me and nobody else.”

Dylan’s recent albums similarly show that he is not only a legend living on old material. “Time Out of Mind,” the eloquently poignant and award-winning album about his struggles with romance, was then his first album of original material in seven years. 2001’s “Love and Theft” received similar acclaim for its richness. Concert goers can look forward to hearing selections from both.

Dylan keeps on making beautiful music and selling out concerts — to curious kids, to obsessed college students and to their parents. “How many years can a mountain exist before it is washed to the sea?” Apparently 63 years — and, one hopes, longer.