Some of the most exquisite moments of the local music scene occur when the Renaissance & Baroque Society of Pittsburgh invokes the first part of its name. It's no secret or shame that the truly early music plays second fiddle to the Baroque, but every so often it's nice to dip a little deeper in the musical chronology. Saturday, it was the renowned Hilliard Ensemble vocal quartet in a program of Dufay and Josquin at Calvary Episcopal Church in Shadyside.

There's two major reasons the vocal music of the Renaissance, roughly spanning the years 1450-1600, takes a back seat to Bach and beyond. One, its texts are almost entirely church Latin or non-English, being liturgical or at least religious. Two, the compositional language is polyphonic. Basically that means different-but-equal melodic lines entwined around each other versus a melodic line that subordinates the others for harmony. It doesn't sound much like the music we commonly hear today. To me, the differences are what makes Renaissance music scintillating -- the crystalline beauty of this music is unmatched -- but there is no doubt this music is distant from today.

Dufay stands at the beginning of the Renaissance, creating architectural masterpieces in sound, while Josquin wrote more pliable art later in the high point of the period. If you pinned me down to ask for top composers of each period, Josquin would represent this one, right up there with Bach and Beethoven as giants of their time. For that reason, Saturday's program was a bit odd. The two composers weren't presented equally.

While Josquin's portions were smaller, idiomatic occasional works, Dufay's contribution was a mass, "Missa Se la Face ay Pale," a more conservative form. The result was a concert where one sat through the latter composer to get to the former, as the movements of the Dufay mass were split up among the program. It would have been better to hear some of the amazing smaller works by Dufay.

Luckily, there was plenty of amazing Josquin to make it worth it. The composer's "Ave Maria" is one of the most expressive and gorgeous works ever written, abounding with ecstatic manifestation of the composer's love for the Virgin Mary in an expanding motif. "Planxit autem David" and "De Profundis" are more low-key, but blossom into vertical outbursts of joy. "Tu solus qui facis mirabilia" is slow and devout, nearly devoid of counterpoint in a self-effacing and almost ascetic fashion. The group sang all of these (and an encore of contemporary composer Arvo Part's "Most Holy Mother of God") with a remarkable interiority. The singers focused on the proper relationship of one phrase to another or to the text, rather than singing certain ones out for effect.

While its musicianship is unassailable, and basics of intonation and ensemble were flawless, Hilliard struggled to project in massive Calvary Episcopal. Here is where its insistence of only one person to a part fell short. Academic arguments aside as to how many did sing this music, it should saturate the audience. In volume alone there were times when it didn't wash over the patrons. This was music composed for use, not written to be observed, in today's concert sense.

Its ability to inspire worshipers was dependent on touching them sonically. In this regard, more singers would have increased the energy and outreach of the performance Saturday, a better solution than the quartet hurting its concordance by trying to sing out louder. This music may be centuries removed, but it is still a living art that can affect us all when we can feel it as well as hear it.