Even if he hadn't composed a single opera, Claudio Monteverdi would still belong to the greatest of the great for his achievements as a master of sacred music. His Vespro della Beata Vergine, published in 1610, is hailed as a landmark of the literature – and is the work instantly conjured whenever you hear the phrase "the Monteverdi Vespers." But it was an altogether different setting of the Vespers service that Early Music Seattle presented at this concert, the most recent installment in the ongoing Northwest Baroque Masterworks Project.

Titled Monteverdi's Christmas Vespers, the programme offered a remarkable and deeply satisfying antidote to the offenses of rote holiday music – and a host of fresh discoveries even for the seasoned early music afficionado. David Fallis, a Toronto-based expert in the field who helms the Toronto Consort and is music director of Opera Atelier, assembled a kind of speculative Venetian Vespers, taking as his chief source the vast anthology of sacred music that Monteverdi published near the end of his long life, in 1640-41: Selva morale e spirituale (Moral and Spiritual Forest). 

This immensely varied collection – the first gathering of sacred music that Monteverdi published since his 1610 Vespro – represents a summation of the composer's experience since he took up his post in 1613 as maestro di capella at San Marco (which, at the time, served as the chapel for the Doge of Venice rather than as La Serenissima's cathedral). These pieces were meant to be taken and arranged as needed for varying contexts. Fallis compiled a sequence of psalm settings and motets, along with an elaborate hymn and the second of the two Magnificats (for eight voices) contained in Selva morale e spirituale, to form a complete musical service that could plausibly have been performed for the First Vespers of Christmas. Supplemented by contributions from a few other composers, the result was a large-scale choral-instrumental work (about two hours, including an intermission) intended to convey the lavish splendour of a Venetian Christmas Eve celebration in the middle of the 17th century. 

Such an imaginary recreation has precedents, whether in Paul McCreesh's Venetian Vespers with the Gabrieli Consort or La Venexiana's version of a Mass to celebrate the end of the plague in Venice. Indeed, the modern rediscovery of the 1610 Vespers itself involves a reconstruction of sorts, since the original publication was arguably intended less as a unified work than as a flexible collection of pieces available to be excerpted (essentially, as a job application to enable Monteverdi to escape his unhappy situation at Gonzaga's court).

So, too, as with any contemporary performance of Monteverdi, myriad decisions must be made as to instrumentation and vocal casting. The early music specialists gathered for the Christmas Vespers included 14 instrumentalists and eight solo singers, with occasional reinforcements by the Seattle Monteverdi Choir (21 voices). Comprising the instrumental ensemble were two violins, tenor viola da gamba, cello, double bass, a pair of cornetti, four sackbuts, and a continuo of theorbo, lute, and organ, all of them first-rate players who were also fascinating to watch as they performed this glorious, so excitingly in-the-moment music. The eight solo singers were separated into two quartets on either side of Fallis. Each displayed a unique colour and disposition, with particularly gratifying results in the soprano duet O bone Jesu (Arwen Myers and Danielle Sampson).

As with the familiar 1610 Vespers, this reimagined Christmas Vespers contained a wondrous variety of combinations and palettes: from all of the soloists joined with the instrumental forces – the sackbuts impressively undergirding the whole with a sense of hieratic joy – in pillar-like sections to duets and solos with only whispery continuo accompaniment. Fallis elicited a refined but always animated clarity across this spectrum of Monteverdian textures, conducting expressively with his hands and stepping aside for the most chamber-like numbers. Especially impressive was the dramatic arc he shaped to unify this richness: even with passages as full of pathos as the motet Canzonetta spirituale sopra alla nanna – a dark, sighing gloss on the simple lullaby genre, in which Mary foresees her child's future Passion – the Christmas Vespers culminated persuasively in the Magnificat and its radiant vision. Along the way, Fallis and his ensemble emphasised the central role of the incisive rhythms that give the music such suppleness. 

The Canzonetta was actually the work of Tarquinio Merula, one of three Monteverdi contemporaries whose music Fallis interpolated alongside the spine of antiphons (the men's voices in plainchant), psalms, and motets that lead up to the climactic Magnificat. A purely instrumental sonata interlude by Giovanni Battista Buonamente further enhanced the Russian nesting doll-like variety of the whole.

Though the intimacy of the venue could hardly mimic the sonorous antiphonal acoustics of San Marco, Fallis attempted to give at least a small-scale taste by having the two tenors (Colin Balzer and Kevin Skelton) sing from opposite perches in the gallery in the poignant motet Salve Regina. Yet even without the reverberant sonic glory of the church that was Monteverdi's laboratory for decades, the performance captivated throughout.