Go ahead. Dump your copy of Reunion, the 1999 live double CD by the shambling version of Black Sabbath that toured a few years ago. This set, made up of recordings from the band's 1970s glory years, not only stomps all over Reunion; it ought to leave most contemporary doom bands quivering in submission to the ultimate masters of the heavy rock form.
The thing that becomes clearest upon hearing this collection is just how tight and locked into one another Sabbath's players were in the band's prime. The perfect proof of this is "Wicked World," a debut-album cut transformed here into a jazz-metal workout unlike anything the band's contemporaries would ever have essayed. It simultaneously reaffirms Sabbath's roots in blues-rock jamming and takes crushingly heavy rock into the stratosphere.
Past Lives also provides a concrete reminder of just how great a singer and frontman Ozzy was in the 1970s. Sure, there's a missed lyric or two here, but his voice is at full strength, not the hoarse croak of today, and his between-song patter is not only coherent, but decipherable. Past Lives is an absolutely essential Sabbath purchase, to be put right beside the first six studio albums in every serious metal/hard rock record collection.