Like the man who composed it, Stravinsky's Symphony of Psalms is a work of great contrasts. Commissioned in 1930 by Serge Koussevitzky to celebrate the 50th anniversary of the Boston Symphony Orchestra, it's not a traditional symphony but a large work for orchestra and chorus in three movements, usually performed with almost no pause. Stravinsky tried to avoid expressing personal emotion, yet this work, with its wonderful textures and sonorities, is profoundly moving. He dispensed with violins, violas, and clarinets--instruments favored by romantic composers--and added two pianos, a harp, and percussion. The first movement begins starkly: the pianos and timpani play a loud chord together, and the woodwinds follow with a repetitive, jazzy, arabesquelike figure. Voices begin rhythmically chanting the Latin text of Psalm 38, a meditative two-note melody that suggests intense prayer. The second movement's powerful double fugue starts with a slow-moving, high-pitched oboe, followed by a flute; the theme allows for plenty of dissonance, and the soprano's ethereal singing of Psalm 39 is haunting. The final movement begins gently with the opening alleluia of Psalm 150, then becomes a slow laudate refrain. An aggressive use of the brass follows--the text reads "Praise him with trumpets....Praise him with cymbals"--and the work ends with the soothing words of the remainder of the psalm. Also on the program are Benjamin Britten's powerful, pacifist Ballad of Heroes (1939), a cantata with soloist (soprano Alyssa Bennett) that includes themes and techniques he later used in his monumental War Requiem, and Gustav Holst's The Planets, from 1916. Christopher Bell conducts. See also Saturday. Fri 8/5, 6:30 PM, Pritzker Pavilion, Millennium Park, 100 N. Michigan, 312-742-4763. Free.