Saturday night at Mount Vernon College, the Musica Antiqua ensemble explored one of the richest themes of medieval art: the image of the goddess Fortuna. In the Middle Ages, even the most devout Christians were likely to pay homage to this pagan deity, who was in charge of the distribution of luck. She appears in the poetry, music and visual arts of that era more than any other female personage except the Virgin Mary, and she was invoked almost as ardently as the Virgin by soldiers, politicians and students, among others -- not to mention the gamblers who are her natural constituents.

The "Wheel of Fortune," today merely a fancy nickname for a roulette wheel, is a basic motif of medieval iconography with a moralistic message: All are subject to Fortune, even the mightiest, and those who are on top today may be plunged into disaster tomorrow. This bit of image-building even secured for Fortuna a place in the facades and stained glass of some cathedrals. Some of the songs addressed to her (notably the great "Fortuna Desperata") were later worked into the texture of liturgical settings, and thus her music as well as her image found its way into the holiest of precincts.

The words of the songs performed by Musica Antiqua abounded with such expressions as "false fortune," "fickle fortune," "bitter fortune" and "desperate fortune," reflecting a time when people felt even less in control of their destinies than they feel today, and it was almost a shocking contrast when Cipriano de Rore's tribute to "benign fortune" appeared on the program.

In a sense, the remainder of the program served mainly to create a context for the "Kyrie" and "Sanctus" of Jacob Obrecht's "Missa Fortuna Desperata," a masterpiece that should be ranked with the great masses of Bach, Mozart and Beethoven. These pieces were beautifully performed by the group, which is fine in instrumental and solo vocal music but at its best in ensemble singing.