None of these catch fire like those classic Stax sessions or, for that matter, like classic Snoop. But it's still moving to see the extent to which artists separated by decades and by genre are simpatico. Frayser Boy—enormous, studious, and almost shy—seems quietly beside himself at meeting Bobby Rush and performing with a live band for what he says is his first time ever. The 83-year-old Bobby Bland, ailing and in a wheelchair for what will be his last session, gives 10-year-old rapper Lil P-Nut lessons in how to sing Ray Charles. Snoop listens rapt as William Bell describes the brutality of the Jim Crow south, and how police on the road regularly harassed him.

As this suggests, the film's interest in contemporary performers doesn't rob it of a sense of history. On the contrary, in between its rap/blues/soul collaborations, Take Me to the River talks extensively about the history of segregation, black pride, and civil rights. Isaac Hayes is shown onstage with Jesse Jackson, and various interviewees talk about how the white establishment in Memphis was angered by wealthy black musicians driving around in flashy cars. There's a substantial, painful sequence about Martin Luther Kings's assassination in Memphis, and the subsequent riots, during which black performers had to escort white performers through the streets to get to their integrated sessions. The violence devastated the neighborhood around Stax; several commenters suggest that the aftershocks, and antipathy from the white music business establishment, helped shutter the studio in 1975.

The documentary's willingness to engage with soul's racial history was not inevitable. As one contrast, Paige McGinley notes in her new book Staging the Blues, the blues-tourism industry in the Mississippi delta generally ignores any discussion of racial inequity. McGinley points out that Clarksdale, a center of Delta blues tourism, had an important history of civil-rights activism that "the city does not acknowledge … in any formal way." She adds that "what is most notable about blues tourism in the Delta is what is not said or included in its itineraries; detailed histories of slavery and sharecropping, the contributions of women to blues innovation, and accounts of civil rights boycotts, Freedom Rides, and desegregation."

The other thing that is left out of blues-tourism, McGinley says, is young contemporary performers. "Clarksdale rappers," she says, "remain largely invisible to the blues-tourism industry," despite the fact that their music, like the fetishized early blues, is based in endurance and resistance to segregation. Or I should say, not despite the fact, but because of it. Much of the warm fuzzy nostalgia for the old blues necessitates a forgetting of the context in which that music was made, and that in turn requires an erasure of our present context, complete with our present music.

Take Me To the River doesn't eschew nostalgia altogether—one commenter launches into an obligatory kids-these-days-autotune-is-awful rant while Frayser Boy stands by nodding and looking charmingly uncomfortable. But for the most part, the love and reverence for the past is balanced by a love and reverence for the present, which for the old hands means both teaching the kids and being wowed by them. As excited as Snoop is to work with Bell, Bell is every bit as delighted by Snoop's wrote-it-in-five-minutes-deliver-it-cold virtuosic rap. As thrilled as students at the Stax Music Academy are to work with the great soul/funk guitarist Charles Pitts, he's just that pleased at the time-keeping of the 16-year-old drummer.