Gratitude is a superimposition of two transpositions of Messiaen's third mode. While searching around for a starting point this week, I was checking out what kinds of chords can be derived out of mode three, and I found that an augmented triad could be constructed on all scale degrees. After discovering this, I had the idea of trying to use only augmented chords, but as I began, I found myself desiring a greater variety of chords. I do use a lot of augmented chords and arpeggios, often with another note added.
I also decided that I should once again make use of non-retrogradable rhythms. Each measure features a non-retrogradable rhythm in the top staff. At first, I scored it with time signatures, which were changing measure to measure. Then I realized that they would be of no use to me as I played the piece, and that I was counting eighth notes in small units (three for a dotted quarter note, four for a half note, etc.) and would be completely ignoring the 13/8 marking at the beginning of the bar. Messiaen writes about this in The Technique of My Musical Language, explaining how a composer is free to use time signatures or not when writing these rhythms. I remember being puzzled by the missing time signatures in score of The Quartet For the End of Time, before reading The Technique. In some instances, such as in Gratitude, time signatures are just not necessary, even when the meter is changing continually.
The photo I used for the SoundCloud file is one of George Ohsawa, the founder of modern macrobiotics. His writings are remarkable. Check him out.