Though it may be a vague and cloudy thought, I often return to the metaphor of “surface” as a way of describing pieces of music. It seems particularly useful when thinking about the music made in or around New York (and, to a lesser extent San Francisco) during the 1960s and 1970s. Morton Feldman wrote in 1976 that it was his primary concern, throughout his work and particularly with For Frank O’Hara (1973), “to sustain a ‘flat surface.’” Feldman had explored the idea more seriously in 1969, detailing a conversation with the artist and critic Brian O’Doherty, wherein O’Doherty made a valiant attempt to define what is meant by a music’s “surface,” and how it is distinct from that of a painting. “The composer’s surface is an illusion into which he puts something real — sound,” said O’Doherty. “The painter’s surface is something real from which he creates an illusion.”