Cappella Clausura’s last concert of this season, Saturday night at Emmanuel Church, opened with vocal music from Ordo Virtutum (The Play of Virtues), by the extraordinary 12^th-century mystic, Benedictine abbess, and healer Hildegard von Bingen, the “standard bearer for women composers,” as conductor Amelia LeClair wrote in her notes. “Her music is unique, her texts are unique, and the fact that she confesses to being the author of her works is unique for her time.” Sung in a circle, the three selections were “Qui sunt hi,” “O Antiqui Sancti,” and “Nos sumus radices,” with “O Deus, qui est tu?” as daring in its questioning as in its Dorian mode (D octave white notes). Here Hildegard makes daring leaps, intervals unknown elsewhere in chant, presumably forbidden.

An inspired and gifted choral leader, LeClair creates programs in which composers and their pieces speak to and reflect on one another: the chant composed by Hildegard ended up as the inspiration for the music on the second half, Hillary Tann’s beautiful Exultet Terra.

Cappella Clausura, originally programming rarely or never heard choral music by women, changed their rules a few years ago to include works by men. Popular Estonian composer Arvo Pärt came next on the program, represented by his celestial “I Am the True Vine” with the immortal words from John: “This is my commandment, That ye love one another, as I have loved you. Greater love hath no man than this: that a man lay down his life for his friends.”

That was followed “Lux Aurumque” (“Light, warm and heavy, they sing and sing and sing to the newborn babe.”) by the popular American choral composer Eric Whitacre, who has become so widely performed that he has been compared to Andrew Lloyd Webber. “Dissonances from close harmonies, that’s my true name,” he has explained on YouTube. “I try to make every moment an ecstatic experience.” This “Lux Aurumque” was deeply peaceful and altogether gorgeous; one immediately hears why he is so popular. His next piece “A Boy and A Girl” was hypnotically slow, full of humming, lovely. In between came another Pärt, “Bogoróditse dyévo,” about the Virgin; these expertly sung introductions to Pärt and Whitacre were most enjoyable.

After Pärt’s “Tribute to Caesar”, a slowish, austere, almost grim piece, full of the composer’s trademark static triads, we heard Whitacre’s “Sleep” (poem by Charles Anthony Silvestri), full of easy-to-listen-to harmonies and my favorite piece in this first half. The chorus (16, four per part) walked out while singing “sleep,” leaving just the women in a circle; they then sang Hildegard’s “O Deus” from the Ordo Virtutum. All eight intoned the same mesmerizing notes. A most unusual and delightful first half.

The important piece after intermission was by contemporary Welsh composer Hilary Tann, who was in the audience. Her “Exultet Terra” consists of five movements for five double reeds and double chorus. The texts are all by the Welsh-born George Herbert “at his most ecstatic,” she remarked at the post-concert talk. “I loved the conceit of this poetry…. I am a word person as well as a note person.” Indeed. Embedded in these songs are all sorts of clever wordplay. LeClair’s notes explain: “Paradise” prunes each ending word by one letter (start, tart, art). “Colos” includes a hidden inner text running diagonally down through the poem. “Heaven” echoes the final syllable with a new rhyming word. And “Exultet Terra” is a textual and musical answer to Hildegard’s eternal question.”

The distinguished double reed quintet (oboists Peggy Pearson and Jennifer Slowik, English hornist Barbara Lafitte, and bassoonists Tom Stephenson and Stephanie Busby) was superb throughout the Tann. The composer has written an oboe concerto and knows how to make the instrument sound fabulous; it didn’t hurt that Peggy Pearson played many of these songs. Cappella Clausura boasts “music you won’t hear anywhere else!” and is certainly to be thanked for introducing this charming work, sung and played so exquisitely. There was a plangent oboe and English horn duet, a wonderful interlude with two bassoons and English horn, and in “Laudate Dominum” Pearson played solo intermittently with the singers as did all five double reeds during the last movement, the exuberant “Jubilate Domino, Omnis Terra.” Tann charmed during the talk, describing the double reeds as “earth-belonging instruments” (to go with the poetry) and remarking that “In Wales we have a lot of aspens,” which translates from Welsh as “women’s tongues”. “I couldn’t imagine setting a tree to a square rhythm!”, so she used a lot of 2+3 and 3+2. In “Jubilate,” she recalls, “Okay, I’m going to make a noise!” and the noise made was exuberant indeed. Brave to Amelia LeClair and her excellent musicians.

Susan Miron is a book critic, essayist, and harpist. Her last two CDs featured her transcriptions of keyboard music of Domenico Scarlatti.