Questlove's 1969 concert doc offers a thrilling and illuminating look back.

In an era when no local block party, let alone a Glastonbury or Bonnaroo, goes undocumented, it's almost impossible to imagine an event like 1969's Harlem Cultural Festival being lost to history — particularly not with a lineup that included Nina Simone, Stevie Wonder, B.B. King, the Staples Singers, and Sly & the Family Stone, nearly all at or near their prime.

The reason for that is pretty much implied in the subtitle of Ahmir "Questlove" Thompson's  Summer of Soul (...Or, When the Revolution Could Not Be Televised); though it was also the chance to bring it all back to the spotlight after more than 50 years that compelled the Roots drummer, DJ, and semiprofessional musicologist to take his first swing at directing a feature documentary. The result, maybe unsurprisingly, is a kind of pure fan's love letter, but still a rich and joyful one to experience secondhand.

A lot of that is thanks to the reams of footage he was able to free from a literal basement, none of it publicly seen before. Though the festival (actually a series of shows spread across the summer) happened within weeks and 100 miles of Woodstock, its own more Afrocentric fusing of popular music, politics, and counterculture proved much less compelling to the general public than whatever was happening on a farm upstate.

Soul (which premiered Thursday night at the Sundance Film Festival) is approximately half concert movie, and Thompson crafts it as a sort of perfect mixtape: The Fifth Dimension's sunny crossover harmonies into the soaring Pentecostal gospel of Edwin Hawkin Singers, through Sly and Stevie and the South African jazz great Hugh Masekala. Mahalia Jackson and Mavis Staples sing each other to heaven on the hymn "Take My Hand Precious Lord"; Max Roach and Abbey Lincoln slink in like the king and queen of be-bop cool; Sly Stone blows the lid off, a tiny tornado in purple satin and suede fringe.

The singularly fierce presence of Simone — her performance is as much a consciousness-raising as a concert — clarifies the movie's other main focus: the concurrent rise of Black pride and cultural identity epicentered in cities like Harlem at exactly that moment in time. To make those connections, Thompson tends to graft music too neatly to nearly every issue of the day, from the Apollo 11 moon landing to Vietnam, explicitly tracing the lines he doesn't always seem to trust his audience to find.

That still allows for some extraordinary moments along the way, many of them directly from the mouths of surviving artists and organizers and bystanders: Jesse Jackson recounts for the camera in detail the last moments of Martin Luther King's life, as footage from him telling roughly the same story half a century ago is intercut; Gladys Knight reminisces about the early days of Motown, and Mavis about the sheer awe of singing with Mahalia. The interviews are their own historical document, though it's the visceral thrill of being inside all those archival clips — the flick of Simone's wrist, an ecstatic face in the crowd — that makes Summer of Soul comes most fully alive, somehow both as fresh as yesterday and as far away as the moon. Grade: B+

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