Book excerpt: From the age of Aristotle to the age of AIDS, writers, thinkers, performers and activists have wresteled with what "performance" is all about. At the same moment, "performativity"--a new concept in language theory--has become a ubiquitous term in literary studies. This volume grapples with the nature of these two key terms whose traces can be found everywhere: in the theatre, in the streets, in philosophy, in questions of race and gender, and in the sentences we speak.