The secret history of contemporary dance music has only become clear in hindsight. In the early ’90s, aficionados realized that electronic music reconciled American hip hop with English acid house, while drawing from elements as diverse as Jamaican dub and German disco. But supposedly it had nothing to do with blues and soul and rock ‘n’ roll.

“Play,” Moby’s sixth album, proves that’s a lie. As a veteran dance artist and cultural provocateur, Moby is smart enough to know that the continuum of African-American music includes disco, rap, techno and house alongside older idioms. On his cunningly crafted CD, the restless techno composer cleverly constructs a bridge between electronic dance music and the black Southern styles that form the basis of most American rock and pop. Sampling numerous early blues and gospel singers over the dance-floor beats on “Play,” he daringly brings the story of black American music full circle.

While that sounds ambitious — if not arrogant — Moby’s disc holds up well next to another startling new release. “Afro-American Blues and Game Songs,” part of Rounder’s ambitious 100-CD Library of Congress reissue series, was originally documented by the nomadic father-and-son folklorists John and Alan Lomax, mainly in the late ’30s and early ’40s. Their haunting collection, which includes Negro hollers, work songs, country blues and children’s tunes — as well as the earliest recordings of blues legends Muddy Waters and Sonny Terry — is an eerie testament to the vital force of raw human expression.

Within a few years of his historic sessions for Alan Lomax, Muddy Waters had moved from the Stovall, Miss., cotton plantation to Chicago, one man among millions to make the great black migration north. Working the day shift and making music by night, Waters learned to amplify his mesmerizing blues to make them heard above the din of the city. There, playing the taprooms of Chicago’s South Side, he set the stage for the 40-year primacy of the electric guitar and the hegemony of rock.

Oddly enough, this is where Moby comes in. The 33-year-old musician from Connecticut came of age at a time after the commodification of music had already turned rock into both a thriving business and an aesthetic battlefield. A young Richard Melville Hall became a member of the resistance, fronting suburban punk bands like the Vatican Commandos. But hard-core got stale. Moby used the lessons he’d learned as a punk and transformed himself into a techno artist. Electronic music, which could be made by one person with fairly inexpensive machines, worked with punk’s guiding do-it-yourself principle. It also let him personally overthrow the ubiquitous, guitar-dominated music of his youth. (Moby’s been known to carry this contrarian impulse way too far: Two years ago, while pundits were proclaiming the death of alternative rock and the arrival of electronica, he released “Animal Rights,” his dreary punk album.)

With his early ’90s anthem “Go,” Moby became the first American electronic musician in that wave of what the press called “electronica” to make a name for himself in his home country. As a militantly outspoken vegan, Christian and animal-rights activist, he earned a reputation as something of a humanist in a notably mechanistic, soulless field.

On “Play,” Moby shies away from purely electronic techno in an effort to emphasize the human component of his music. Given his objective, it makes sense that he’d look to the recordings of Alan Lomax for source material. Several of the samples on “Play” come from Lomax’s four-disc set “Sounds of the South: A Musical Journey From the Georgia Sea Islands to the Mississippi Delta,” commissioned by Atlantic in 1959, released on LP in ’61 and reissued in ’93 on CD. Moby doesn’t pretend to have hunted through dusty 78s at the Library of Congress; he found them on CD at Tower Records in New York City.

With nearly every imaginable kind of music already devoured by sample-hungry DJs, it’s hard to believe that more electronic musicians haven’t yet explored this black roots music. Moby must have known he was on to something. “Play” is front-loaded with three bluesy numbers in its first four tracks, the simple, inherently catchy repetitions of the blues form dovetailing perfectly with the circular nature of his dance grooves.

Moby’s obvious emotional response to his source music — the way he uses voice as pure sound — feels almost intuitive. Boy Blue’s lonesome howl permeates “Find My Baby” and the Shining Light Gospel Choir pleads desperately for salvation in “Why Does My Heart Feel So Bad?” But he admits that there’s a deeper truth at work here: As a Christian, Moby finds both comfort and common ground in the lyrics of his gospel material. Fatboy Slim’s recent hit “Praise You,” which lifted a dated gospel chorus, secularized a religious song with winking irony. But on Moby’s track, the vocals sound earnestly appreciative.

Among the album’s best tracks is “Natural Blues,” in which Moby samples the singer Vera Hall. While that particular vocal came from “Sounds of the South,” Hall also has two pieces on “Afro-American Blues and Game Songs.” She’s as potent in Moby’s hands as she was a cappella, the ghost of her voice resonating as if she were still alive.

If those voices constantly evoke an image of Moby searching for the roots of electronic music, he finally draws a line straight from the Mississippi Delta to the South Bronx, connecting the dots of black American music. On “Bodyrock,” he samples Spoonie Gee & the Treacherous Three, mashing up their old-school “Love Rap” with brash funk-rock guitars, a bit of jazzy electric piano and a big, insistently up-to-date groove. It’s a gambit that’s consistent with Moby’s historical imperative, proving that blues, rock, rap and the latest dance beats are not only compatible, but malleable, timeless and equally beautiful.