Time Circle (1968-1972) (1991)

Driven by an even greater desire for creative exploration, the chameleonlike Spirit took the eclecticism of Southern California as its guiding principle. The double-disc Time Circle explores the group's multifaceted mixture of rock, jazz, and Brit-conscious pop, interspersing terse rock gems — smart, hard-edged creations like ''1984,'' ''I Got a Line on You,'' and ''Aren't You Glad'' — with jazz-oriented instrumental excursions, including ''Taurus,'' to which Led Zeppelin's ''Stairway to Heaven'' owes a significant debt. B+