This video was recorded during a live concert of my organ compositions on May 26, 2012. The great organ at Vilnius University St. John's church works well for this kind of writing, I think.
The piece is constructed in this way: at the beginning it starts with a short introduction in which the right hand part plays sixteenth note ostinato motive in high range on a flute stop over second inversion seventh chords played by the left hand and feet which play a long sustained pedal point.
The chant presented in the right hand and pedals at the same time alternates with this episode of sixteenth notes. I think what makes this little piece quite colorful is the Ionian mode (just like in natural major) presented in several modulations with the relationship of the minor third. In other words, the modes are transposed a minor third up or down from time to time.
This is not a difficult piece to learn, by the way. All you need is a little of hand and feet coordination during the two episodes where the chant is presented. However, all these colors have a flip side also - sometimes there are quite a few sharps or flats next to the treble and bass clefs in the score.
By the way, do you want to learn my special powerful techniques which help me to master any piece of organ music up to 10 times faster? If so, download my video Organ Practice Guide.