On the other hand, perhaps such effluvium is exacly why the author never attempts a similar definition nor establishes an aesthetic foundation for the music lest he appear somewhat unhinged, or drugged, the latter of which would not be an unreasonable assumption as unreserved drug use (especially hallucinogenics like LSD, mescaline, and Ecstasy), intense spirituality, or both, figure prominently in the life and work of virtually every musician profiled in this book. It is strange indeed to read such a serious and intellectually rigorous a book that takes such an uncritical, downright Pollyannish view of drug use.

Throughout the entire book I was waiting for Prendergrast to say, "Just kidding," as he gushed about LSD opening the doors of perception for the psychedelic generation of the '60s, or Ecstasy changing "the course of popular music at the end of the twentieth century, effecting the way it was made, listened to and enjoyed...After the three- or four-hour high, Ecstasy had a slow glowing comedown, perfect for listening to quieter music. Hence Ambient [music] became popular..."

All of this may be true, but even Timothy Leary acknowledged various potential downsides to drug use, including psychosis, disregard for personal hygiene, and death.

The term "ambient music" was coined by one of the book's heroes Brian Eno in the '70s as he attempted to "synthesize the work of the primary Minimalist composers and bring it into the mainstream." Eno variously described the music as "an immersive, environmental experience," and "music that would take on the hues of the environment just as the color of the light and the sound of the rain," which is rather subjective but can be reasonably applied to most of the music discussed in the book.

Other commonalities include a "lightness," a "transcendence," a "coolness," and the influence of non-Western trance musics from Asia, Africa and Eastern Europe. Interestingly, the author includes virtually no actual non-Western music in his book, just the Western music it influenced. I have no argument whatsoever with the author's "Essential 100 Recordings of Twentieth-century Ambience," an invaluable guide to the music - it is, in fact, perhaps the best definition of ambience extant.