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.