Soul music began to drift away from gritty, deep sounds in the late '60s, moving back toward smooth, immaculately produced uptown soul, but this time there was a difference. Taking their cue from the pop-oriented records of Motown, the purveyors of early-'70s soul threw everything in the mix. Not only were there impassioned vocals and sexy rhythms, but also pop productions, sound effects, psychedelic flourishes, elements of reggae, and Latin inflections. Soul had not been this ambitious in years and, as the first 15 volumes of Rhino's multi-disc series Soul Hits of the '70s: Didn't It Blow Your Mind! illustrate, it was frequently as good as anything released in the '70s. Due to contractual reasons, some big names, including Al Green, Stevie Wonder, and Marvin Gaye, aren't included on Didn't It Blow Your Mind!, but they aren't missed because the overall quality of the material is so shockingly strong. The Spinners establish themselves as the finest vocal group of the '70s, but the Delfonics, the Chi-Lites, the Chairmen of the Board, and many others give them a run for their money. And while Curtis Mayfield stands out from the competition, that doesn't diminish the worth of Eddie Holman, Freda Payne, or any of the other lesser-known artists. In fact, one of the main pleasures of this set is discovering so many one-hit wonders who released singles as good as the major artists. There are a few misses on the first 15 volumes but, by and large, each collection is terrific; in addition to being sold separately, the first five volumes were also packaged together in a slipcase, providing a good entryway to one of the finest various-artists collections ever assembled.