On July 29, 1966, Bob Dylan became distracted while riding his motorcycle. Nobody knows what caught his eye—he told Sam Shepard that it was the sun; he told the biographer Robert Shelton that he hit an oil slick—but he ended up at the bottom of a hill in Woodstock, New York, with his Triumph beside him. His thoughts could have been distraction enough. Two months earlier, his band had finished a four-month run of shows that had become, as the critic Greil Marcus described, “increasingly embattled and defiant.” This was in keeping with the mood of Dylan’s live performances for the past year. When he took the stage at the Newport Folk Festival the previous July, with an electric guitar and a rock band, he pushed his career into a sharp turn. It seemed like a betrayal to those fans who thought that Dylan was Dylan only when he was carrying an acoustic guitar and singing obliquely political songs like “Blowin’ in the Wind.” Many of his followers thought that he was more than a musician. In Manchester, England, two months before the accident, someone cried out “Judas!” during Dylan’s set. It’s likely that Dylan knew how pop idolatry worked, but being roped into the Last Supper, even if you expected a few disciples, must have been unsettling. It’s not hard to imagine Dylan wanting to get off the road, where he’d lived more or less since 1961.

There is no official documentation of the accident, and it’s not clear what injuries Dylan incurred, though he said that he suffered a concussion and “busted” some “neck vertebrae.” It is also unclear how many people witnessed the accident—Dylan said that his wife, Sara Lowndes, was behind him, in a car. “It happened one morning, after I’d been up for three days,” he said. He told one interviewer, “I probably would have died, if I had kept on going the way I had been.”

After a short convalescence, Dylan tinkered with a tour documentary he was making, called “Eat the Document.” (It has never been commercially released, but bootleg copies have circulated for years.) In the spring of 1967, he began making music again. He worked in his house and in the basement of a house outside Saugerties, near Woodstock, with his touring band, a mostly Canadian group originally called the Hawks and later renamed The Band. He performed no live dates in 1967, made a single appearance in 1968, and played only three shows in 1969. He removed himself from public view for all of 1970, and then, in 1971, he appeared at the Concert for Bangladesh, a benefit in New York organized by George Harrison. That year, he told Shelton, “Until the accident, I was living music twenty-four hours a day.” In the summer of 1967, he was recording music without living it, or living it differently from before. The recordings he made in Woodstock are a document of Dylan determining where he and his songs and his audience and his country and his past overlapped, or didn’t.

Next week, a six-CD set called “The Basement Tapes Complete: The Bootleg Series, Vol. 11,” featuring a hundred and thirty-nine songs, will be released. It is not exactly an album, and was never intended to be. Some of the songs began circulating in 1969, on an album that came to be called “The Great White Wonder,” and brought the word “bootleg” into the context of music. Six years later, sixteen songs from these sessions, plus eight written and recorded by The Band alone, were enhanced with overdubs and officially released as a two-LP set, under the name “The Basement Tapes.” Several months before the release, Dylan gave his first radio interview in nine years and said, “Somebody mentioned it was a good idea to put it out, you know, as a record, so people could hear it in its entirety and know exactly what we were doing up there in those years.” Dylan eventually moved the project from arm’s length to an even more distant spot. In 1984, he told Rolling Stone, “I never really liked ‘The Basement Tapes.’ I mean, they were just songs we had done for the publishing company, as I remember. They were used only for other artists to record those songs. I wouldn’t have put ’em out.” The public wasn’t quite as skeptical. In 1975, Robert Christgau gave the album one of his rare A-plus grades and wrote, “This is the best album of 1975. It would have been the best album of 1967 too. And it’s sure to sound great in 1983.”

Dylan was woodshedding with musicians he had known mostly onstage—Robbie Robertson, Garth Hudson, Rick Danko, Richard Manuel, and Levon Helm. He was rummaging through American popular music to find sounds that might resonate and free him from whatever self he had created. Dylan had débuted as a thinly disguised Woody Guthrie imitator, turned into a folk-song writer of fearsome economy, and was moving into a third phase, which he described, in a 1978 interview, as “that thin, that wild-mercury sound,” referring to albums like “Blonde on Blonde” (1966) and the electric albums before it. (In the same interview, he also called this style “the sound of the streets with the sunrays” and “all pretty natural sounds,” a contradiction that works in a song but less well as an explanation.)

“The Basement Tapes Complete” reveals a reluctant prophet and his new friends looking for something. Their search was wide and lacked dogma. The Band was catching the new songs that Dylan was rapidly writing, and following along as he recalled a Halloween bowl’s worth of old American songs. Bob Nolan’s country standard “Cool Water” belonged to everybody; “People Get Ready” belonged mostly to Curtis Mayfield; and “Folsom Prison Blues” was, and still is, very much Johnny Cash’s song. “I Shall Be Released” could easily have emerged in the late eighteen-hundreds, from a factory or a farm or any part of America that wasn’t level with the rest of the country. But Bob Dylan wrote it. No matter how many times he told the world to stop asking him questions, he kept writing songs that felt like answers, and not just for Americans. The Band recorded the song for its first album, “Music from Big Pink,” in 1968. My favorite version of “I Shall Be Released,” though, is the springy, ecstatic version released in 1976 by the Jamaican vocal trio the Heptones, who changed “my light” to “Jah’s light.” If the motorcycle accident was perhaps not life threatening, the throwaway writing sessions were not so tossed off. “The Basement Tapes Complete” is proof that, after the accident, Dylan didn’t so much change his set list as his language, and the language of the American songbook.

In October, 1979, Dylan and his band were playing “Gotta Serve Somebody” on “Saturday Night Live.” He looked distracted—he was wearing a windbreaker and shuffling, as if he were about to bolt the studio to catch the Staten Island Ferry. The music was limp, like reggae played by people who had read about it but never heard it. Dylan sang, or spoke, lyrics about “the heavyweight champion of the world,” someone with “women in a cage,” and “the head of some big TV network,” and about how, at the end of the day, these big cheeses all had to serve somebody. I was twelve, and even then I could tell that he was setting up straw men as some ridiculous proof that religious faith was universally necessary. This was the revolutionary guy that people droned on about? I was becoming obsessed with music. My city, mostly limited to Brooklyn at that point, was roughed up and broken, and I needed a sound that matched that environment. Whatever I was looking for wasn’t in what Dylan was selling, a rough paste of obeisance and crabby lecturing. I was already tired of the dopey “everybody must get stoned” song—“Rainy Day Women #12 and 35”—that WNEW 102.7 still played, thirteen years after its release. Sixties nostalgia was in full swing before the seventies ended.