There’s nothing quite as exhilarating as the slap in the face delivered by the belated discovery of genius: where has Veljo Tormis been all my life, and why hasn’t someone alerted me to his existence?

The first Baltic Sea Festival came into its own with the superb Estonian Philharmonic Chamber Choir’s unforgettable all-Tormis concert at Stockholm’s Berwaldhallen. Many who attended will never be quite the same. (A rush on the woman selling the chorus’s CDs from a suitcase in the lobby left people haggling over last copies. “We never expected them to sell,” she apologised when her stock was quickly depleted.)

Almost all of the 24 numbers were drawn from the epic song cycles which comprise Tormis’s Forgotten Peoples,composed between 1970 and 1989. Grouped under titles such as “Karelian Destiny”, “Vespian Paths”, and “Votic Wedding Songs”, Tormis based his songs on ancient aboriginal folk music of vanishing cultures of the Balto-Finnic region. Some of the dense harmonics, complex rhythms, and tonal intervals foreign to western ears (seconds, fourths, and sixths) are redolent of the a cappella Bulgarian folk music popularised by a series of recordings in the 1990s.

For part of the concert, the 27 chorus members and conductor Tönu Kaljuste sat in a circle, giving the feeling that we were being allowed to observe a secret, arcane ceremony.

Two independent compositions,Curse Upon Iron and Litany To Thunder, are among the most fascinating, joltingly original compositions I have ever encountered. In Curse Upon Iron, Kaljuste led with beats from a handheld drumskin, ritualistically moving among the chorus as if a possessed shaman, while soloists Mati Turi and Allan Vurma sang, chanted, and created rhythmic patterns through repetition of guttural consonants of the Estonian language.

As Kaljuste observed about Estonia’s two greatest contemporary composers, “If Arvo Pärt’s music is heaven, then Veljo Tormis’s music is earth.” Even with humorous numbers (in an utterly charming pussy-cat song, the men purr while the women meow), this mystic, poetic music is more profoundly moving and powerful than words can suggest: it demands to be experienced.