A solitary voice: "I believe in one God."

Then a second voice: "I believe in one God."

Then another, then another, then another: "I believe in one God..." soon the whole room is full of people confessing their shared faith.

Bach sets this simple text (the beginning of the Nicene Creed) to a simple seven-note tune, but spirals it out into a seven-voice fugue that ranks up there with the most complex pieces of harmonic work of the baroque era.  And yet, despite the remarkable density of the counterpoint, the music sounds effortless and light.

"Credo in unum Deum" from the Mass in B minor, Netherlands Bach Society, conducted by Jos Van Veldhoven: https://youtu.be/3FLbiDrn8IE?t=3254