Best known for sealing in amber the most remarkable talents of the Chicago blues scene's early days—before the scene became an exhausted cliché and fodder for celebrity-owned theme restaurants—the Chess label has had a long and varied history, a history that has in recent years been repackaged and reissued numerous times. With 1997 marking the 50th anniversary of Phil and Leonard Chess' first venture into recording, it's time for another series of reissues. That's nothing to complain about; with figures as monumental as Muddy Waters, Howlin' Wolf, Bo Diddley and Chuck Berry occupying the Chess label's vaults, there's probably always room for more material. These three two-disc sets all take previously unused, and very satisfying, approaches. Before Chess, there was the fledgling Aristocrat label. In order to capitalize on the popularity of blues music among the many post-War transplanted Southerners, the Chess brothers—two Polish immigrants with a flair for business—set about recording the area's music for the already-existing label they would eventually take over. Captured on the Aristocrat set are some of the earliest examples of Chicago blues, including music by Sunnyland Slim and Muddy Waters. It's the inclusion of this material—amongst such obscurities as "Bilbo Is Dead," a politically explosive number in its time, and "Forest Sykes Plays The Blues," a perfectly good blues song recorded by a man who no living person connected with the label can remember—that puts this material in its proper historical context. That the music is generally memorable doesn't hurt things, either. As the '50s dawned, the Chess brothers took over the label, lent it their name, and began producing the blues that would provide the inspiration for rock music in the coming decades. That relationship is explored on The Chess Blues-Rock Songbook, which includes the original versions of nearly 40 songs later covered by the likes of John Mellencamp, Credence Clearwater Revival, Led Zeppelin, Elvis Costello, Van Halen and many others. That the originals are united here only because of the oft-inferior work of those who covered them—when's the last time you voluntarily listened to Canned Heat or Ten Years After?—is the only quibble to be had with this remarkable set. Because even bad musicians tend to gravitate toward strong material, the collection includes some of the strongest performances recorded for Chess during its heyday, making it an indispensable piece of music history. In the '60s, soul was ascendant, and Chess couldn't quite keep up. Aside from the towering "Rescue Me" by Aretha Franklin clone Fontella Bass, Chess was never a success on par with labels like Motown, Stax or Atlantic. Still, the label produced some strong singles that found a welcoming home in the British Northern Soul movement; they still sound good today, though they get less distinctive toward the end of the decade as the task of production was farmed out to other studios. Chess Soul may be the weakest of the three collections, but it's only weak in a relative sense. It can stand proudly beside the other two as testaments to one of the most important labels in the history of blues, rock and soul music.