Understanding the Organ Music of Olivier Messiaen: Optical Illusions Versus Aural Realities

In this thesis, I examine the organ music of Olivier Messiaen both from the viewpoint of a theorist and as an organist. I assert that not only his influences, but also his in-depth understandings of the mutations stops of the organ and what pitches are produced by using these stops inform Messiaen\u27s music. Furthermore, the organ music requires more than mere visual inspection, but must be aurally experienced because of the registration requirements placed in the score by Messiaen. The utilization of mutations often does not produce concert pitch, but other pitches absent in the score. To demonstrate this I provide numerous musical examples throughout this document. Furthermore, I assert that Messiaen\u27s deliberate use of mutation stops is a part of his musical and harmonic language often overlooked as colorful or mere tone painting