This definitive study takes as its subject a group of melodies copied many times, even within single manuscripts. Professor Randel is therefore able to base his conclusions about the relationship of the manuscript sources to one another on twenty-six separate Spanish manuscripts. He shows that there were actually four distinct traditions associated with these manuscripts instead of two as formerly assumed. By comparing the four traditions, he draws new conclusions about the relative antiquity of the written tradition for these psalm tones, the presence or absence of a modal system in the...