Koussevitzky's interpretation of Bach's Mass in B Minor yesterday afternoon and evening in Symphony Hall would not have satisfied a purist. The retards on cadences were exaggerated, the orchestral part at the end of "Et Resurrexit" was omitted and so was the first Osanna. The soles were taken more slowly than regulation, particularly the bass aria, "Et in Spiritum Sanctum," for it is quite frankly a pastoral dance, inspired by the word "Vivificantem" (Giver of life).

But only the most complete purist would not have been pretty deeply affected by the whole thing. It is quite a privilege to be able to hear the Mass at all no matter what the interpretation. In fact, I think those who managed to get seats were among the luckiest people in the world yesterday. And if their standing ovation for all participants is any indication, they thought so too.

Soloists, orchestra, and all 300 members of the Glee Club and Choral Society deserved every bit of it. They did everything that Koussevitzky told them to do, and since he was the boss, that is the highest praise they could be given.

Of course, the number of performers ruled out any possibility for delicate treatment in choral passages. The Mass can be as effective in mightiness as in subtlety, however, if the chorus is well enough trained to execute cleanly the variations in volume derived from the counterpoint itself. The Glee Club and Choral Society were. After the some-what uninspired reading of the Kyrie, in which lone syllables appeared and vanished with no apparent intention, the Chorus climbed to heights of accuracy and cooperation in the Gloria. The "Qui Tollis" was an achievement which is impossible to describe, and the transition without pause from subdued "Quoniam" to the crashing joy of the "Cum Sancto Spritu" was one of the most dramatic moments I have ever heard in music. Though things, got a little out of control in the "Et Resurrexit," the chorus redeemed itself in a powerful and cleanout performance of the "Sanetus."

This is an appropriate place to heap superlatives on G. Wallace Woodworth. There is probably no more challenging work in all musical literature than the B Minor Mass, and enormous ambition and perseverance are required to undertake it at all. In addition, Woodworth's philosophy of Bach is almost the antithesis of Koussevitzky's yet he trained the Chorus to respond with complete accuracy to the Conductor's direction. This achievement is even more remarkable when you realize that Woodworth had to substitute for Koussevitzky in the only complete rehearsal with the Orchestra.

The soloists both vocal and instrumental, were unformly good. Special notice must go to Leo Wolovsky, the bass. Though he suffered some in the "Quonian" from the competition of the horn, he showed complete understanding of words and music in the "Et in Spiritum Sanetum," with enough technical skill to make both apparent.

This is a symbolic year for Koussevitzky, and the performance yesterday was in a sense a personal triumph for him. In adding things up, however, the honors must be distributed just as generously elsewhere.