Crosby and Nash at the Arlington

Almost 40 years after the release of their first album together, legendary classic rockers David Crosby and Graham Nash took the stage of the Arlington Theatre this past Sunday — delivering a decades-defying dual performance that boasted enough energy and rock ‘n’ roll enthusiasm to put the almost-sold-out S.B. crowd into a Woodstock-era state of mind.

The band opened the show with the twangy guitar intro to Crosby and Nash’s 1969 hit “Marrakesh Express.” As soon as the duo — noted for their distinctive melodies and unparalleled vocal harmonies — belted the song’s first few notes, their voices had the ecstatic crowd engaged in a joyful, trance-like sing-a-long, which continued throughout the three-hour-long set.

The pair’s eclectic setlist showcased many of C&N’s beloved ‘70s-era hits, as well as several new, rarely heard tracks. During the first act, the two Rock and Roll Hall-of-Famers played some of their most popular tracks, including Billboard-topping songs like “It’s Been a Long Time Coming,” “Just a Song Before I Go,” and “Guinevere,” — some of which were originally written with one-time partners Stephen Stills and Neil Young, during a period Nash affectionately referred to as the CSNY “era.” Crosby made for a memorable start to the second act, opening with the iconic “Our House.” Falling abruptly silent where he was expected to take lead vocals on the song’s final chorus, Crosby reached his hands into the crowd — as if to hand over his mic — and a welcoming thousand-voice choir of audience members took over, singing, “it’s a very very very fine house.”

After a mellow start, Crosby and Nash’s combined youth-like energy grew, starting with a barefoot Nash, who traded in his acoustic guitar for an electric and announced the band was about to perform some new material. Among the best new works were Crosby’s upbeat “Camera,” which he wrote about his filmmaker father, and “Don’t Dig Here,” written by C&N keyboardist James Raymond — who, to the surprise of most of the audience, was introduced as Crosby’s own son. The band also debuted “A Slice of Time,” a song they revealed had never been performed for a live audience before. Crosby and Nash closed their set to a standing ovation, and bid the audience farewell with an unforgettable acoustic rendition of the harmony-laden, lullaby-like ballad “Teach Your Children.”

Crosby and Nash’s 1971 album Another Stoney Evening was re-released this week, and the duo humbly remarked on stage how amazed they still feel that crowds turn out to see them. C&N fans might say it’s because of the pair’s ability to maintain their energetic, youth-like vigor on stage, even after decades of touring; or, that they possess that one-of-a-kind wisdom that only legendary musical virtuosos do. But Crosby — who spent his primary and high school years in S.B. County — offered his own take: “[This is] what happens when you sit up in Santa Ynez all day, watching the cows.”