by Richard S. GinellStillness is a concept album -- the title tune opens and closes it in moody stillness -- and a transition piece all at once, for Sergio Mendes seemed to be searching for a viable way out of the Brasil '66 formula. Indeed, "Righteous Life," using a different L.A. rhythm section, is really a folk-rock record, a good one, and a far cry from the bossa-propelled '60s. So is the funky voodoo cover of Stephen Stills' "For What It's Worth" in its own way, though the old Brasil '66 sound does come in very handy in a superb treatment of another folk-rock song, Joni Mitchell's "Chelsea Morning." Yet Mendes also experiments with different, more authentically Brazilian rhythm patterns in a brilliantly propulsive rendition of Gilberto Gil's "Viramundo" and a lovely Oscar Castro-Neves/Sebastiao Neto tone poem, "Celebration of the Sunrise." This would also be Lani Hall's farewell to Sergio Mendes, leaving the band in mid-album on the way to becoming Mrs. Herb Alpert and starting a solo career, to be replaced by the Brazilian Gracinha Leporace, who is now Mrs. Sergio Mendes. Overlooked in its day, Stillness is the great sleeper album of Sergio Mendes' first A&M period.