There's a line that can be drawn between Led Zeppelin's first four albums and their last four. From 1969 through 1971 -- the period that spans their self-titled debut through their untitled fourth record -- Led Zeppelin played the blues, sometimes twisting and evolving it to their modern, heavy sound (like they did on their fourth LP), other times just lifting it outright (see their first three albums, particularly the first two).

These periods can also be tidily divided between their lean, hungry years and the bloated superstar band they became around 1973 or so. So it's no accident that their BBC recordings stopped in 1971, a few months before the release of their monumental fourth album made them untouchable.

Listening to the Led Zeppelin on The Complete BBC Sessions is a way different experience than listening to the Led Zeppelin from The Song Remains the Same. On that 1976 live soundtrack LP, they thought they were the best live band on the planet; on the expanded three-disc Complete BBC Sessions, they actually come close to it.

This expanded edition of the band's 1997 album includes remastered versions of the original two dozen tracks plus nine additional songs left off the record at the time. The sessions include six appearances on various BBC programs -- some recorded in the studio, some recorded live (like the 1971 London concert that makes up disc two).

Most of the new tracks are repeats of songs already found on the earlier set in different form -- two more versions of "Communication Breakdown" and "What Is and What Should Never Be" are added, as is an 11-minute "Dazed and Confused" that's not as electrifying as the 18-minute one found on the 1997 album -- with the exception of the instrumental "White Summer" (released in edited form on the 1990 box set and in full on 2015's Coda reissue) and "Sunshine Woman," a bluesy vamp from 1969 that was never recorded by the band.

Through it all, Led Zeppelin tear through their catalog with a dynamism that borders on ferocity. Robert Plant grunts and growls with a sexual hunger that consistently weaves in and out of Jimmy Page's guitar. Check out his room-shaking wails on the showstopping "How Many More Times" or his guttural moans on the positively mind-warping "Dazed and Confused" from the 1971 concert.

This is Zeppelin before the rot set in around the time of their 1973 tour. They sound hungry, determined, anxious and aroused. The best songs here -- "You Shook Me" from their first BBC session, "The Girl I Love She Got Long Black Wavy Hair," "Travelling Riverside Blues," "Communication Breakdown" from the new disc -- are essential pieces from the band's formative years.

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