The author would like to thank the following for kind permission to reproduce published material: the Medieval Academy of America (Example 2.5), Willem Rodenhuis, Universiteitsbibliotheek Amsterdam (Examples 3.6 and 3.7); Universal Edition (Example 3.9); Editions de Solesmes, Abbaye Saint-Pierre (Example 3.10), Berandol Music Ltd. (Example 3.13); Kluwer Academic Publishers (Example 3.16), Karlheinz Stockhausen (Example 3.17). Example 3.4 © Ernst Eulenburg and Co. GmbH, Mainz. Reproduced by permission of Schott and Co. Ltd, London (MAHLER). Example 3.12 © MOECK MUSIC, D-Celle for all countries with the exception of: © Schott Musik International, D-Mainz for Poland. Example 3.15 © 1929 by Universal Edition London Ltd. © renewed 1956 by Boosey and Hawkes, Inc., New York. Example 3.14 is reproduced by kind permission of Alice Moyle.