In the 1997 book "Soulsville U.S.A.: The Story of Stax Records," author Rob Bowman called the storied Memphis soul label a "grand accident."

Now the "accident" that gave the world Otis Redding, Sam & Dave, Isaac Hayes and many others, which began as Satellite Records in 1957 and folded 18 years later, has been reactivated, beginning with an ambitious 50th anniversary celebration.

The renaissance includes CD reissues, the signing of new artists, DVD and digital-only releases, and a PBS documentary, and is designed to drive home the social as well as the musical importance of Stax, a multiracial marvel at a time when segregation still ruled in the South.

"There's a line we've been using regularly — that soul began with Stax," said Robert Smith, vice president of strategic marketing for the Concord Music Group, which acquired the Stax catalog from Fantasy Records in 2004. "The celebration of the 50th anniversary of Stax is, very broadly speaking, a celebration of soul music itself."

As Smith acknowledges, the heritage of Stax — aka Soulsville U.S.A. — wasn't ignored before Concord took over; many fine reissues were already available. But this new program, which will extend well beyond this year, is not just about the past.

Out already is a two-CD box containing 50 Stax hits spanning the duration of the label — the first such comprehensive collection, Smith says. Included are a reissue of Carla Thomas' 1969 album, "The Queen Alone"; the release of a 1972 Johnny Taylor performance, "Live at the Summit Club"; and "Interpretations," a new all-star tribute to Earth, Wind & Fire's Maurice White (not a Stax artist, but a native Memphian).

Coming attractions include "Respect Yourself," a two-hour PBS documentary due in August that will also be released on DVD; numerous best-of compilations on Stax artists; and a Christmas set. There also will be albums of new music from returning hero Isaac Hayes and three new signees, singers Angie Stone and Lalah Hathaway, and the jazz-soul-funk band Soulive.

Former Stax singer, songwriter and publicist Deanie Parker, who remains one of the most passionate champions of a label that was the grittier and funkier counterpart to Motown, senses the time is right for this project to flourish.

"I don't know if the marketplace would have appreciated this before," Parker said, pointing to the various musical trends that have come along since Stax filed for bankruptcy in 1975, from disco to "this godawful rap and hip-hop." And one good thing about it happening now, she added, is that many of the original artists are still alive to be appreciated anew.

The City of Memphis itself is in on the Stax hoopla, and will hold a "Seven Days of Soul" extravaganza June 16-22.

William Bell, a key Stax singer and writer responsible for such hits as "You Don't Miss Your Water," points to the crucial role that the camaraderie of black and white music people played in the label's distinctive sound.

"It was more an adventure than work," he said from Atlanta, where he still records and runs his own label, Wilbe. "We were just young kids, and it was like going to university, because we learned our craft and created a whole new genre of music."

To Parker, that touches on what she sees as the label's greatest legacy: "The music is indelible, it is timeless. ... It was not contrived. It was an art form that emanated from people who enjoyed being together, creating the sound. ... It's kind of like love — real love. You can't design it, you can't kill it, you can't redo it — real love. ... It's almost spiritual."