Editing In C (section)

===Performance Practice===
The score's instructions for performers have gone through several iterations.<ref name=Reed/>{{rp|48}} Originally, it had none as musicians played from Riley's [[Ozalid (trade mark)|ozalid]] copies of the score. After the 1968 release of the Columbia [[LP record|LP]], many performances relied on the score that was printed in the album liner.<ref name=Hill/><ref name=Carl/>{{rp|44}} The Soviet premiere, for instance, was made possible because [[Edison Denisov]] passed on his copy of the record to Alexei Lubimov.<ref name=Repit/> The LP includes a terse paragraph, written by David Behrman, that explains how to interpret the score.<ref name=Riley68/> Most musicians were exposed to Behrman's instructions before Riley bothered to write any down.

Riley did eventually pen two pages of handwritten notes to explain how to perform ''In C''.<ref name=Turek/> In 1989, he released a shorter typed set of instructions.<ref name=Riley89>Riley, Terry. ''In C''. Celestial Harmonies, 1989.</ref> The most recent set of instructions from 2005 differ significantly from Riley's originals, and all three are afterthoughts, born from the experience of playing the piece with a wide range of instruments and skill levels.<ref name=Carl/>{{rp|58–60}}

The one thing the composer has stressed in every version of the instructions is listening:
::"Don't be in a hurry to move from figure to figure. Stay on your part and keep repeating it, listening for how it is relating to what the rest of the ensemble is playing."<ref name=Turek/> 
::"It is important to think of patterns [[Period (music)|periodically]] so that when you are resting you are conscious of the larger periodic composite accents that are sounding, and when you re-enter you are aware of what effect your entrance will have on the music’s flow." (1989)<ref name=Riley89/>
::"It is very important that performers listen very carefully to one another and this means to occasionally drop out and listen...One of the joys of playing '''''In C''''' is the interaction of the players in polyrhythmic combinations that spontaneously arise among patterns. Some quite fantastic shapes will arise and disintegrate as the ensemble progresses through the piece." (2005)<ref name=Riley05/>

Behrman's instructions for the album refer to an unwritten part, "Not included in the score is a piano part, called the Pulse, which consists entirely of even octave eighth notes to be drummed steadily on the top two C's of the keyboard throughout the duration of a performance."<ref name=Riley68/> The prevalence of the Pulse on the recording, along with Behrman's note gave rise to the impression that it is a requirement of the piece. One set of liner notes even fetishizes it, "[[In the beginning (phrase)|In the beginning]] was the pulse."<ref>European Music Project, zignorii++, ''In C''. Liner notes by Johannes Ullmaier, trans. Steven Lindberg. WERGO, 2002.</ref>
 
However, Riley's first instructions are more playful and hint at the available leeway, "The pulse is traditionally played by a beautiful girl on the top two octaves of a grand piano. She must play loudly and keep a strict tempo for the entire ensemble to follow."<ref name=Turek>Riley, Terry. ''In C'' in ''Analytical Anthology of Music''. Edited by Ralph Turek. 2nd ed, McGraw-Hill, 1992. 540.</ref><ref>{{cite web|url=https://music.williams.edu/files/2010/01/050708_IN_C_program.pdf|access-date=2025-02-26|title=Terry Riley" ''In C''|date=2007-07-27|publisher=[[Williams College]], Department of Music}}</ref> The current version of the score explicitly makes the Pulse optional, "The ensemble can be aided by the means of an eighth note pulse played on the high C's of a piano or mallet instrument."<ref name=Riley05/>

After decades of familiarity with ''In C'', Riley recognized that the pulse had outlived its usefulness. Technique had advanced to a point where "any good musicians now could keep it together...I don't like The Pulse, as is sometimes used, 'out in front,' where it becomes very annoying. That wasn't my intention of the piece at all."<ref name=Alburger/>{{rp|9}} At the 20th anniversary performance in Hartford, no pulse was used to revelatory effect.<ref name=Potter/>{{rp|111f}}