A preface often speaks of anxiety. When Giulio Caccini published his Le nuove musiche of 1602 he attached a preface to annotate his notation; the notes, he says, ‘are written in one way, but to be more graceful [they] are affected in quite another’. His words carry the anxiety of Baroque performance practice, a fear that always lurks behind the notes whenever a text demands the creative interaction between the performer and the notation; in such cases, the preface greets the reader as a defence mechanism to safeguard the author's intentions, lest the text be misinterpreted. So it is not simply out of politeness that I greet you. This preface is written out of an anxiety about your performance practice. How will you read this book? Will you get it? Let me invoke three words both to guide your reading and to allay my anxiety:

1. Constellation: this word murmurs with the aura of Walter Benjamin. For Benjamin things simply refuse definitions, for a concept cannot live up to the thing it names, but limits the meaning by making it identical to the concept. Similarly, absolute music cannot be defined; its identity is nebulous and its history too volatile to pin down with precision. To write about it as if it were a single, stable concept would miss the point, for its meaning is situated in an ever-changing constellation of elements.