"One of the things we've lost since the Middle Ages is the ability to be terrified by the unknown," tenor and harpist Benjamin Bagby told his audience last night in the University of Maryland's Center of Adult Education. Then he proceeded to give a vivid demonstration of what has been lost in the process of becoming modern.

No melodies have been handed down with the Anglo-Saxon text of "Beowulf," though it is safe to assume that the bloody old epic was not just declaimed but chanted -- perhaps with simple accompaniment on a six-string lyre. That's how Bagby performed more than 100 lines of the poem, describing Beowulf's climactic battle with the monster Grendel.

"Beowulf" might have seemed fairly dry stuff when you read it with a dictionary at your elbow and your professor discussed it in terms of weak verb forms, alliterative versification and the socioeconomic structures of the Anglo-Saxons in the 7th century. Bagby, improvising melodies and using a brilliant array of dramatic and rhetorical techniques, made it a dazzling experience. His performance should be recorded and made required listening for courses in early English literature.

It was only one highlight in a concert given by the Sequentia Ensemble for medieval music, which filled the stage with a tenor, mezzo-soprano and soprano as well as players on the organetto, harp, lyre, fiddle, rebec and symphonia (a sort of hurdy-gurdy, played by turning a crank). This was a particularly neat trick, since there were only three performers: Bagby, Barbara Thornton and Laura Jeppesen.

Jeppesen only sang harmonies and devoted most of her energies to playing the fiddle. Her performance was very effective throughout and brilliant in a long, elaborate, improvised-sounding variation on the anonymous song "Edi be thu hevene-quene," played on the fiddle after it had been sung by Bagby and Thornton. "Edi be thu" is about as close as this concert came to the medieval Top 40 repertoire, and Jeppesen's instrumental jamming on the melody gave it a new twist for those who might have found it familiar.

In English repertoire, which took up all the second half of the concert, Sequentia also performed the three songs of St. Godric, who claimed they had been taught to him by heavenly visitors in visions. Last night's heavenly performance made this claim seem not all that improbable. The other two vocal works in this segment, "Worldes blis" and "Man mei longe lives wene" had rather moralistic texts bidding hearers to reflect on death and eternity. A lot of that sort of thing went on in medieval England. But in this case, the moralistic texts had a saving grace; they were linked to exquisite melodies and very effectively sung.

The first half of the concert also had its geographical focus in England, but it presented songs in French and Provencal that might have been heard at the Anglo-Norman court. These included a superb love song by BerBernart de Ventadorn, the favorite troubadour of Eleanor of Aquitaine, and the lament written by Richard the Lion-Hearted when he was being held for ransom in Germany and none of his friends or relatives seemed eager to provide the money. The performances throughout were as satisfying as the very imaginative programming. This group brings a special color and vitality to its chosen repertoire and will be most welcome when it comes back again