Beautiful Chaos is the arresting title of a book by Carey Perloff, on her life and times as director of the American Conservatory Theater in San Francisco.   I have a partner with 30 years' experience as an actor but I have no professional understanding of the theatre; yet the book engrossed me with its insights into the dynamics of the world backstage.  (Declaration of interest:  Carey is a second cousin of mine, though we've never met.) Two themes in the book struck me particularly.  The first is the emphasis put on theatre as a vehicle for lifelong learning.  At a technical level Carey describes the changes she made to…