I once took a course in graduate school called “Composing for Percussion.” Every week the students were assigned a different instrument for which to write short musical ideas. My classmates seemed taken with my fragmentary idea for three marimbas, so much so that I decided to build a new piece, Drift, from it. Using the fragment as a repeating chaconne progression, I then composed an extended, free-floating cello solo to emerge from and descend into the warm tones of the marimbas.