The best way to describe the pleasures of this two-disc retrospective from the venerable Chicago blues label is to point out what isn't here: no weak or inappropriate material, few over-extended guitar solos, nary a synthesizer or drum machine in earshot. Just pure, honest music of a type few record companies are interested in these days, delivered with the kind of passion that bespeaks a commitment to artistic values over dollar signs. If Malaco, Alligator's chief competitor in the blues market, gets terrific singers (Bobby Bland, Shirley Brown) but often falls victim to a crass standard of chitlin' circuit commercialism, and Delmark, the other big force in Chicago blues, hews closely to tradition, then Alligator lies somewhere in the middle. Founded in 1971 by Bruce Iglauer (a former stock boy at Delmark), it takes its blues seriously but not literally, making records that expand the range of artistic possibilities while remaining grounded in the salty realities that created them in the first place. In fact, one of the great joys of this set is to hear the various manifestations the blues has taken on during its journey from raucous south side barroom (the early tracks by Hound Dog Taylor and Big Walter Horton) to the flash and dazzle of the rock arena (Johnny Winter) and back to the sweet testifying of the African-American church (Mavis Staples). Alligator can be said to have found its greatest success in exploring all the little stops along the way. Elegantly rambunctious second-line piano (Professor Longhair), delicious swamp boogie (the marvelous, much-missed Katie Webster), fluid harp playing (James Cotton), high-voltage guitar (Luther Allison) -- it's all here, and there's not a bad track in the bunch. Fans may quibble with some of the choices (I prefer the Holmes Brothers' "street corner" classicism to the dense rock of their Joan Osborne-produced "Speaking In Tongues"), and the whole project comes off like a bit like those Warner Bros. double-album Loss Leader sets from the early '70s -- more sales brochure than ardent excavation. But, with "from the album" information printed dutifully beneath each track description, this time, at least, listeners will have the right idea.