Earlier this evening I recorded this improvisation in honor of the 2019 Advent season.
The improvisation is based very loosely on the Advent hymn "Veni, Veni, Emmanuel" as well as on the melody of an ancient Greek Orthodox "Kyrie Eleison" chant.
You can listen to the recording here: https://www.reverbnation.com/michaelcalabris/song/31587914-organ-song/31587914-organ-improvisation-for-advent