"The heavenly motions of the planets. A continuous harmony. A song with many voices." Johannes Kepler, 1500 Johannes Kepler was the first to accurately describe the motion of the planets around the sun. In his Harmony of the World, he challenged musicians to set his mathematical formulas to music. I decided to accept his 500 year old challenge to set his mathematical formulas for planetary motion to music. Kepler's theories seem to begin the bridge from what is known as the Dark Ages, to the modern era of enlightenment. I was born and raised in New York City, the son of a rabbi. Questions about our origins and spiritual nature filled the house - as did music. I came of age during the "questioning 60's" at Brown University and dropped pre-med in favor of the music I loved. The spiritual and religious themes from my childhood were awakened by Kepler's theories charting the movement of celestial bodies. "Music Of The Spheres" began with the superimposition of one of Kepler's planetary arrangements on the musical Circle of Fifths. This gave me a road map of musical keys to follow. The mythology of each planet provided the inspiration for melodic, harmonic, rhythmic and textural elements. These musical elements were enhanced by the belief that the position and motion of celestial bodies influence human behavior.