Attending an Anonymous 4 concert is like entering a cloister where disagreeable thoughts are banished and the spirit is cleansed by soothing, unearthly voices. Perhaps that accounts for the a cappella quartet’s rising popularity in these incivil times; perhaps it also explains why the group is warmly embraced by New Agers. But Anonymous 4 is what it has been since its four gifted singers banded together in 1986–a vocal ensemble dedicated to reviving the medieval musical forms of chant and polyphony. On their latest CD, 11,000 Virgins (Harmonia Mundi), they tackle chants written by 12th-century abbess Hildegard von Bingen in honor of Saint Ursula and her maiden army, who were martyred by the Huns, but for this yuletide show, the theme is slightly more cheerful: Susan Hellauer, the musicologist in the group, has selected works that celebrate the exploits of Saint Nicholas, patron of children and itinerants and preserver of ships and sailors. Nicholas, who was expunged from the Vatican’s list of saints in 1969, is believed to have lived in what’s now Turkey until his death on December 6, circa 345. Seven centuries later the removal of his relics to Italy boosted his popularity, and he became a hot liturgical subject. Anonymous 4’s tribute is structured as a loose biography in music that includes hymns, a couple of rhythmically tricky motets, a series of conducti, and readings in English from a 13th-century account of Nicholas’s best-known miracles. The concert takes place at the Fourth Presbyterian Church, that oasis from Boul Mich’s rampant consumerism, thereby providing an extra reminder of the true meaning of Christmas. Friday, 8 PM, 126 E. Chestnut; 312-787-4570 or 773-702-8068. TED SHEN

Art accompanying story in printed newspaper (not available in this archive): photo by Susan Johann.