What's so hard about acting, anyway? A person stands on stage, pretends to be someone else, says a bunch of words, and reveals to an audience what that person is all about: "I wish we could go to Moscow!" "I sure am angry at Uncle Claudius!" "Being a salesman sucks!" But, as the new edition of Routledge's excellent Twentieth Century Performance Reader reminds us, there is a world going on beneath the surface of even the simplest piece of theater: a whole history of thought and analysis, an academic discipline, and a legacy of imagination.

This means, paradoxically, that among the performer's many challenges is to figure out how much of this history to worry about, and how much to forget, when stepping on a stage. Here's director Peter Brook in a 1968 essay excerpted in the Reader, bemoaning the reliance of the theater on its own traditions: "It is vain to pretend that the words we apply to classic plays...have any absolute meaning. They are the reflections of a critical attitude of a particular period, and to attempt to build a performance today to conform to these canons is the most certain road to deadly theatre." Elsewhere, Brook spells Deadly Theatre with a capitals, meaning bad theater: theater that must be saved from itself.

Brook isn't the only one worried about such things. The 20th century, in the realm of performance as in politics or music, was a time of great upheaval. The authors excerpted here have problems with the old ways...and, for the most part they've got solutions. There's the psychological theater of Stanislavski, the total theater of Vsevolod Meyerhold, the political theater of Augusto Boal, the alienation theater of Berthold Brecht, the theater=storytelling=music of Laurie Anderson, etc. And that's just the performance stuff; the book also includes the theories of Isadora Duncan (dance), Adolph Appia (set and light design), and John Cage (I have no idea).

What emerges, somewhat surprisingly, is not a collection about how new technologies have affected the world of performance. There are, of course, occasional reflections on such things as how the cinema has affected the theater (from Robert Lepage, who further explains that his theatrical sense came more from Genesis and Jethro Tull concerts than anything else). But The Twentieth-Century Performance Reader is a book of ideas on how our thoughts about performance, not our machines, have evolved. Robert Wilson and Philip Glass are both represented here and both discuss the creation of Einstein on the Beach, using old ideas about theater and music and performance to create work that is stunning (and daunting) in its originality.

As is so often the case with big anthologies, the editors of this Reader (Michael Huxley and Noel Witts) make some odd choices in the presentation of their material: With each chapter, we get an essay or interview followed by the source citation and footnotes, and only then a little note on the author. (To be fair, these are remarkably informative and concise biographies.) Perhaps it is considered wonderfully avant-garde to make me read something before telling me what it is or exactly who is speaking.

This is not a book from which one could learn how to perform. Even the sections directly addressed to acting students--the bits from Stanislavski's Building a Character or from Julian Beck's Acting Exercises, fore example--are chopped up and excerpted beyond the point where they can be useful as lessons. Nor is this a book for the casual spectator of the theater who does not particularly care how and what goes into a performance as long as it makes him laugh or cry or both. It is a book for us, the enthusiasts, whose enjoyment of performance is enhanced by increased knowledge about the traditions of theater--how those traditions have evolved, and how they've been questioned.