Practically all the program given last night by the Folger Consort involved the joy of discovery, even for confirmed devotees of Medieval and Renaissance music.

Titled "Music from the Edge of the World: Iberia," it must have included a dozen Washington premieres - all the more impressive because the music was four to eight centuries old - and the performances were prime examples of technical skill placed at the service of solid scholarship.

One major discovery was the Catalan "Llibre Vermell," a collection of hymns sung by pilgrims at Monsterrat, some technically elaborate and others clearly rooted in folk music, all melodically fresh and well sung.

In another number, which made a fine duet for baritone Elliot Levine and countertenor Peter Becker, "Ave color vini clari," there was also a religious flavor, complete with an elaborate "Amen," but it was used for the glory of wine.

A section of Christmas songs alternated folk and ecclesiastical flavors - and the Folger group came up with an arrangement of the popular "Riu, Riu," which for once did not echo the popular version of the New York Pro Musica.

The instrumental colors in this concert were somewhat more varied than in the group's debut, with a harp, tambourin" and drums along with the lute, recorders and viols, all played with excellent style.