The Woodstock Music and Arts Fair, which began on Aug. 15, 1969, brought together nearly half a million mostly young Americans for a long weekend of peace and love, along with torrential rain and massive amounts of drugs. History was made, the cultural impact was huge and enduring, and much has been written about the significance of the event. Ironically, what has been least examined is the very thing that brought this throng of unprecedented size together: the music itself—from the inspired to the indifferent.

The impetus for a gathering of hip acts and plugged-in fans wasn’t a new one, of course. The Newport Jazz and Folk festivals had been taking place each summer since the 1950s; it was at the latter that Dylan “went electric” in 1965. But the clear-cut antecedent for the Woodstock Festival was Monterey Pop, held during the Summer of Love, which featured performances by The Who, The Grateful Dead, The Jefferson Airplane, The Paul Butterfield Blues Band, Jimi Hendrix, Janis Joplin, Country Joe & the Fish and Canned Heat, all of whom would come to Max Yasgur’s farm near the village of Bethel, N.Y., 43 miles from Woodstock. The Monterey fest had attracted an estimated 12,000 fans, a good-sized crowd, but not even big enough to fill a basketball arena; the notion of 30 to 40 times that number coming together was all but inconceivable—until it happened.

The first day of Woodstock was envisioned by organizers Michael Lang and Artie Kornfeld as a celebration of folk music, with Joan Baez headlining a bill that contained both known entities and unheralded singer-songwriter Bert Sommer. The scheduled starting time was 4pm, but the already massive traffic jam made the roads into the venue impassable, so Lang and Kornfeld’s original sequence of performers went out the window, as they frantically called for helicopters to bring in the performers—any acts who could get there.

Lang had originally planned to open the show with a set from San Francisco’s Sweetwater, but the band had arrived on the site, and the stage wasn’t yet set up for an electric performance. That left him with two options: Tim Hardin, who was present but wasted, or the more together Richie Havens, who’d arrived on the first chopper (in all, 16 were used during the course of the weekend). “It was who could get setup the quickest?” Lang remembered. “And I went with Richie Havens.” He took the stage at 5:07pm, in front of a crowd already estimated at more than 100,000 and growing exponentially—and only 60,000 had been anticipated for the entire festival.

Havens ended his hour-long set with the improvised “Freedom,” which is now remembered as his big moment, thanks to Michael Wadleigh’s 1970 film, Woodstock, and by then the stage crew was ready for Sweetwater. Ironically, they’d been shuttled in on a U.S. Army helicopter. “If it wasn’t for the U.S. Army, Woodstock might not have happened,” Havens later said, acutely aware of the irony. “We were never anti-soldier,” he pointed out. “We were just against the war.”

After getting a lift to his car on a chopper, Havens drove back to Newark International Airport, where he caught a plane for a Saturday-night date in Michigan. “I was the only person on the New York Thruway going south,” he wryly noted.

The female-fronted Sweetwater followed with a set of folk-rock in the mold of the early Jefferson Airplane, to a polite response. The crowd perked up considerably when Bert Sommer took the stage and filled the 60-acre site with his powerfully melodious tenor and crisply constructed songs. The performance of this forgotten singer-songwriter is downright revelatory—primarily because hardly anyone has heard what he was capable of until now. What this set suggests is that if Sommer had been on Elektra or Warner Bros.—or if he hadn’t been passed over for Wadleigh’s film—he might’ve wound up with a career like that of Tim Buckley, whose music and vocal acuity are the closest parallel to what he thrillingly delivered in his performance. It’s now apparent that this talented artist, whom history has passed by, provided the absolute highlight of the first day.

By the time Sommer had finished his breathtaking set, Hardin was sufficiently together to take the stage, and his jazz-inflected poignancy came through on “How Can We Hang On to a Dream” and “Sing a Song of Freedom,” two of his signature songs—though the acoustic jams that took up a good part of his performance didn’t come close to what he was capable pulling off of on a good night.

It began to rain as Ravi Shankar took the stage to play a characteristically proficient set, though by all accounts he was extremely unhappy about both the weather and the crowd. That most certainly was the case, because the sitar master chose to completely re-record the set in a Los Angeles studio, which is what you hear on Shankar’s 1970 release on World Pacific, Live at the Woodstock Festival.

The Incredible String Band was due up next, but they refused to play in what was by then a driving rainstorm. Melanie Safka, a virtually unknown 22-year-old singer-songwriter, had been pestering Lang to let her sing for the crowd, so he sent her onstage for an unscheduled performance. “It was the only out-of-body experience of my life,” she admitted. “I just watched myself onstage singing the songs, but I wasn’t there.” Out of body or not, she came through like a veteran, as the movie demonstrated, and her lilting performance, inspired numerous people in the throng to light candles, which they managed despite the downpour. We can only assume that the crowd found Melanie sufficiently cute, vulnerable and brave to inspire this spontaneous gesture, but the moment seemed downright mystical, deepening the already palpable sense that something extraordinary was going down—and giving the young artist enough career momentum to take her to the mid-’70s. The experience inspired her to pen the hit “(Lay Down) Candles in the Rain.”

While Arlo Guthrie and his sidemen turned in a solid performance, he ignored shouted requests for “Alice’s Restaurant” throughout the set, causing us to wonder how rock history would have been altered if he’d just given in and played the epic song while Wadleigh’s cameras rolled.

Baez was six months pregnant, and her husband David Harris had been taken into custody by Federal marshals—a topic that dominated her stage patter. Despite these preoccupations, she closed out the first day with a pristine set that intermixed the traditional material she’d been singing for a decade with country-rock selections written by Gram Parsons during his stint with The Byrds. Baez finished around 3am, with the rain still coming down.

Adapted from the notes to Woodstock: 40th Anniversary Edition (Rhino, 2009).