To perform his father's score, C.P.E. had to alter the instrumentation slightly. The intervening years had seen the disappearance of the oboe d'amore (one of dad's favorite instruments). C.P.E also decided to have the orchestra double the choir in a few movements, perhaps because the singers in his Hamburg were not used to such elaborate polyphony. He also wrote an instrumental introduction to the work based on a German hymn. This piece, a lovely five-voice setting for strings in an organ prelude style, was new to me. Though Friday's performance got off to a bit of a rocky start tuning-wise, I was still impressed by the sweetness of the music.

The “Credo” itself was stupendous as ever. Though tuning continued to be a problem in the orchestra, the choir reached the heights they have achieved under Stewart's direction. The central grouping of “Et incarnatus est,” “Crucifixus,” and “Et resurrexit” showed the choir's affective flexibility. With a unity of sound and vision, this volunteer group created a moving experience of the “Credo's” passion in miniature.

The “Credo” includes just two sections for soloists. The duet “Et in unum Dominum,” sung by soprano Ruth Escher and alto Suzanne Elder Wallace, was lovely. Unfortunately, it was also hard to hear from where I was sitting in St. Mark's, Berkeley. Volume was not a problem for bass Hugh Davies, however. His rendition of the “Et in Spiritum Sanctum” was hypnotic.

Hearing the aria and chorus from Handel's Messiah in German was another new experience. Ruth Escher performed the familiar “I know that my Redeemer liveth” in the new guise of “Ich weiß, daß mein Erlöser lebet.” Her lovely clear soprano glided beautifully over the familiar harmonies of the orchestra. Even more familiar was the “Hallelujah” Chorus. The stirring sounds of the orchestra and chorus brought the audience to its feet, according to the tradition supposedly started by England's king in the 18th century. It was a fine close to the first half of the program.

The second half included two works by C.P.E. himself: a short orchestral symphony and his “Magnificat.” Not knowing which symphony appeared on the original program, Stewart chose the first of the younger Bach's four orchestral symphonies that date from his years in Hamburg. It is also in the sunny key of D major, which both Bachs used in their “Magnificat” settings. Stewart's small ensemble (all one on a part, save for the violins) rocked their way through this stormy, passionate piece. A nice surprise was the lovely cello solo in the Largo played by Elisabeth Reed (who should get a medal for playing the entirety of this lengthy program).

Originally written in 1749, C.P.E. revisited his “Magnificat” in the 1780s, reworking the scoring of some movements and writing a new setting of the “Et misericordia.” Instead of the duet it once had been, the new “Et misericordia” utilizes the full choir in a highly chromatic way. Wandering harmonies longing for resolution characterize this version, touchingly performed by the California Bach Society.

Another high point was Dan Hutchings' performance of the demanding “Quia fecit mihi magna.” This piece is particularly tricky for the ensemble. Hutchings remained focused throughout, his clear tenor easily soaring through the long melismas.

All stops were pulled out for the grand finale of “Sicut erat in principio.” With orchestra and chorus going full force, I felt I would be carried away by the waves of sound washing through St. Mark's. Perhaps I was indeed carried back to Hamburg in 1786: one of the nicest things about this evening was that the audience behaved in a historically-informed manner as well, clapping wherever they felt like it. In this program, with the fine soloists and choir of the California Bach Society, that was often. Congratulations and best wishes to Warren Stewart, and I look forward to hearing what the talented Suzanne Elder Wallace will do with the group as its new artistic director.