Vespers are the ancient prayers of the evening, a ritual that has inspired beautiful music for centuries. If one were asked to choose the most glorious, the clear choice would be Claudio Monteverdi's "Vespers of the Blessed Virgin." Sublime melodies revolve around a tonal axis, Gregorian shadows surround each prayer, and colors arise that remain as fresh as a child's first rainbow. It is an extremely difficult work, but one whose greatness can be contemplated even in a partially successful performance. The Oratorio Society of Washington gave it such a performance last night at the Kennedy Center.

The augmented choral forces were impressive if not subtle, but at times the sheer size of the vocal fabric tended to cover the orchestral details. It was like trying to view delicate lace through velvet. The strings of the Concert Soloists of Washington were stylish, the winds and brass less careful. Around the middle of the Magnificat that closes the work the instrumental sound fell apart in intonation and phrasing and was saved only by aggressive singing at the end.

The eight principal singers were quite fine, with a particularly rewarding set of tenors. There was true beauty and simple greatness when Gene Tucker sang the Virgin's name and the sound returned in Stanley Cornett's tenor with a freshness all its own. The blend of the soloists was often lovely, and all at least tried to avoid bel canto anachronisms in their singing.