"The structure of Music for 18 Musicians is based on a cycle of eleven chords played at the very beginning of the piece and repeated at the end. All the instruments and voices play or sing the pulsating notes with each chord. Instruments like the strings which to not have to breath nevertheless follow the rise and fall of the breath by following the breathing patterns of the bass clarinet. Each chord is held for the duration of two breaths, and the next chord is gradually introduced, and so on, until all eleven are played and the ensemble returns to the first chord. The first pulsing chord is then maintained by two pianos and two marimbas. While this pulsing chord is held for about five minutes a small piece is constructed on it. When this piece is completed there is a sudden change to the second chord, and a second small piece or section is constructed. This means that each chord that might have taken fifteen or twenty seconds to play in the opening section is then stretched out as the basic pulsing melody for a five minute piece very much as a single note in a cantus firmus, or chant melody of a 12th century Organum by Perotin might be stretched out for several minutes as the harmonic centre for a section of the Organum. The opening eleven chord cycle of Music for 18 Musicians is a kind of pulsing cantus for the entire piece."
-Steve Reich
As of this upload, it is the only YouTube video that has the correct second chord in both written and audio form.
![](https://s2.save4k.ru/pic/N-iZMw8VBR0/maxresdefault.jpg)