Montserrat Figueras and Jordi Savall at the Lobero

Often invoked as a principle of judgment, either positively or negatively, authenticity in musical performance eludes precise definition. Hesperion XXI plays music from the 10th to the 18th centuries on original instruments and in carefully researched period arrangements, but they do so in front of microphones, and on Thursday this quartet version of the group reached its audience at the Lobero in part through amplification. Violist Jordi Savall, soprano Montserrat Figueras, percussionist and flutist Pierre Hamon, and string player Dmitri Psonis performed the music of several centuries, and in the process they engaged in a substantial amount of improvisation. Yet the overriding sense, rather than that of pastiche or modernization, was of the full, unconditional presence and authority of tradition. Hesperion’s approach embodies an absolute and unswerving devotion to meaning and history that effectively neutralizes contemporary concerns with such matters as individual virtuosity, compositional innovation, and the commoditization of technique. This is music primeval, a wellspring experience that transcends distinctions between sacred and secular, and erases the artificial boundaries of period style.

This particular concert, titled Lux Feminae 900-1600, was dedicated to celebrating seven manifestations of the feminine spirit in song. Drawing equally from the Jewish, Christian, and Muslim traditions, and singing in Latin and Spanish as well as playing cithara, Montserrat Figueras was the beating heart of the presentation, her long dark hair worn loose over a simple red tunic. Her husband Jordi Savall, the founder and leader of Hesperion XXI, echoed his wife’s ensemble in reverse, wearing a red scarf over black and maintaining a peaceful gravity as he paced the music from behind his rebab and lira da gamba. Pierre Hamon opened the evening by walking the left-hand aisle while playing a flute and drum, and Figueras and Dmitri Psonis joined him for the exit march at the end of the long single set.

Although all of the evening’s music was of an unchallenged high quality, the encore nevertheless moved this listener beyond anything that came before. Figueras and Savall’s son Ferran joined his parents onstage, standing close enough to his mother that his voice could be heard through her body microphone. Together they improvised a heartbreaking lullaby, a grown son fully inhabiting the imaginative universe painstakingly created by his parents, and by entering it, affirming its validity for another generation.