When the Harvard-Radcliffe Collegium Musicum gives a concert, they know how to do it in style. Their performance last Friday of the Monteverdi Vespers of 1610, in celebration of their 25th anniversary, was dazzling in every way, from the period instruments to the virtuosic soloists to the outstanding choir itself.

The program began with a welcome by Professor Thomas Kelly, in which he gave a brief history of the Vespers. Claudio Monteverdi (1567-1643) is believed to have composed this collection of works in thirteen parts for the Gonzaga family, the rulers of the duchy of Mantua, for whom he was court composer. The Vespers is one of the daily hours of Roman Catholic worship, and Monteverdi's Vespers contains the texts of all of the essential prayers: the opening versicle and response, five psalms to the Virgin Mary, the hymn, and the Magnificat. Interwoven in these works is a collection of motets and an instrumental sonata.

The richness of Monteverdi's music is amazing, especially considering the era in which he composed. He uses the full range of colors and emotions available to him through the ancient instruments and voices, as can be heard in his numerous contrasts of tone throughout the Vespers. The psalmic settings (which were numbered incorrectly in the program except for Psalm 147) follow the Gregorian chant, but with great variations. On the other hand, the motets employs a style radical for those times: the "monody" or duet writing, which has a bolder and more expressive sound. Particularly beautiful is the transition from his hymn Ave maris stella (XII) to the concluding Magnificat (XIII). These two movements exhibit all the richness of sound and tonal imagination that make the Vespers such an outstanding work.

Perhaps the most eye-catching element when one first looked upon the stage Friday night was the Boston Shawm & Sackbut Ensemble with its unusual ancient instruments. Directed by Daniel Stillman, this group provided excellent accompaniment for the choir and soloists. They had a warm, clear, and muted sound typical of Renaissance instruments that showcased their musicality but never overshadowed the singers. It was especially interesting to note how the two players of the violini da brazzo (precursors to the modern violin) held their instruments in the crook of the arm, rather than under the chin. These two violini had a notable interplay of melody in verse seven of the Magnificat. Also, the instrumental sonata (Sancta Maria, XI) provided the audience with the pleasure of hearing the Ensemble alone, and basking in the clarion sound of the ancient instruments.

The soloists--Ellen Hargis, soprano, Laurie Monahan, mezzo soprano, William Hite, Frank Kelley and Arthur Rishi, tenors, and Paul Guttry and David Ripley, bass--were superb as well. Hargis was particularly impressive; she is a specialist in pre-Baroque music, and it shows. She captured the Renaissance style perfectly, demonstrating complete control over her voice so that there was no excessive vibrato, yet no shrill tone. Also greatly enjoyable was the tenor dialogue in the Audi coelum (IX), in which Hite sang his responses to Kelley from the balcony.

And the Collegium Musicum itself? Over and over again, it amazed the audience with its rich, warm sound and stunning musicality. Director Jameson Marvin deserves much acclaim for his skill at directing Renaissance music, and for achieving the delicate blend of voice parts that marks this group. Especially in Psalm 112 (IV), it was delightful to hear how such a large choir could sing with such precision and in such a light and dancing style. The soprano section sounded particularly beautiful as a foil to the ancient instruments. Verse five of the Magnificat featured a marvelous interplay of male and female voice echoing one another. The whole of the Magnificat was a shout of triumph for this group, as they swept the audience up in the excitement of the concluding chorus.

Indeed, this was a performance to remember. The packed audience in Sanders Theater gave these musicians a much-deserved standing ovation, having experienced one of the greatest concerts to have come to Harvard this year.