A sense of something infinitely greater than the small self or troubling ego rises in the serene opening of Morten Lauridsen’s “Lux aeterna” (1997). This haunting work for choir and orchestra confirmed its composer’s place among the most sincere and convincing voices in contemporary choral music, and underlined his credentials as a true American original. Born in 1943, Lauridsen grew up surrounded by the awe-inspiring nature of southeastern Washington and worked at first for the United States Forest Service, discovering his vocation in music while watching for fires on his isolated beat near Mount St. Helens. A sage or seer in the mold of Henry David Thoreau, Lauridsen combines an engaging simplicity of musical expression with the kaleidoscopic intricacies of contrapuntal lines that appear connected to prehistory. The emotional impact of his works can be overwhelming, as so in the motet “O Magnum Mysterium” (1994), an intense projection of the mystery of God’s incarnation and of reverential wonder in the created universe.