"Did it even begin accidentally when some singers strayed from their single line of plainchant and made concordant sounds? We will probably never know."
That was how Deborah Roberts, joint artistic director of the 2017 Brighton Early Music Festival (BREMF), introduced the riddle in her programme notes for Plainsong to Polyphony, a superbly curated concert at St Bartholomew's Church, Brighton, dipping admittedly only a toe into the vast ocean that is more than 500 years of sacred, sung early music.
In keeping with the festival's Roots theme, digging deeply into where classical music came from, the evening felt like the listening equivalent of watching a time-lapse film of an acorn growing into a giant oak.
A humble processional chant began the metaphorical life cycle followed by the only-recently-discovered earliest piece of notated polyphony, Sancte Bonifati (Anon), dating back to about 900.
As we time-travelled through the distant centuries, the types of polyphony and chant branched out in ever-increasing sophistication, thanks to the dedication to their art of the gifted amateur performers of the BREMF Consort of Voices and The Lacock Scholars, directed by Deborah Roberts and Greg Skidmore respectively.
This was very much a movable feast of music, clusters of singers popping up in different locations, including Arts and Crafts designer Henry Wilson's red, green and black marble pulpit.
In the cavernous Italian Gothic-style setting of St Bartholomew's, the tallest parish church in Britain, if not Europe, there was arguably only one way to cap a memorable evening.
So it was that singers from both groups congregated at the back of the nave to conjure up a wondrous wall of sound in Thomas Tallis's transcendental 40-part motet, Spem in alium, composed in about 1570.
This was polyphony in excelsis in a church described by John Betjeman as a "tall sanctuary of peace. Its interior awes beholders to silence."
Blessed with the musical key to the everlasting, Tallis had just happened to write the definitive anthem for the mindfulness generation of 450 years later.