Photos by Andy Tullis / The Bulletin Director Clyde Thompson leads the 40-voice Central Oregon Mastersingers during last Sunday’s rehearsal Local voices Central Oregon Mastersingers begins its 7th season By David Jasper / The Bulletin Published: October 21. 2011 4:00AM PST The 40-piece Central Oregon Mastersingers will kick off its seventh season tonight at First Presbyterian Church in Bend (see “If you go”) with what director Clyde Thompson promises will be “a big concert.” Thompson is referring to Morten Lauridsen’s “Lux Aeterna” and Leonard Bernstein’s “Chicheste r Psalms,” two pieces that he says are widely considered to be among the greatest choral works by American composers. “They are certainly two of the most popular,” he said. They’re part of a program that also includes choral works by Ralph Vaughan-Williams, Pavel Tschesnokoff and others. All in all, the concert has been a “ pretty big undertaking,” Thompson said last week, adding with a chuckle, “It’s a little bigger even than I realized when we started off.” Since its premiere i n 1997, “Lux Aeterna” has become one of the most frequently performed choral works in the world, according to Thompson. “Lux Aet erna” mean s “Eternal Lig ht,” he said, and “you can hear the image of light pervading the whole 25-minute piece — the textures that Lau ridsen creates for the choir just seem to shimmer. The music has a sort of translucent quality. It’s a gorgeous work.” Lauridsen was awarded the National Medal of Arts in a White House ceremony in 2007, and according to Thompson, musicologist and conductor Nick Strimple has called him “the only American composer in history who can be called a mystic, (whose) probing, serene work contains an elusive and indefinable ingredient which leaves the impression that all the questions have been answered.” The inimitable Leonard Bernstein composed “Chichester Psalms” in 1965 for the annual m usic festival at Eng land’s