Jiří Veltruský (1919-1994) published many articles on various aspects of theatre over the years between 1940 and 1993 but no book-length study, apart from his doctoral dissertation. He was too fully occupied by activities of an entirely different nature. It was only as he was approaching retirement age that he was able to take up the offer of an opportunity to write a book integrating his own earlier studies and other Prague scholars’ work on all the various aspects and components of the theatrical art into a unified theory. He did not live to complete the project but the manuscript he left offered a sufficient account of his theory to make other scholars in the field wish to see it published. It took more time and patience than expected but now, at long last, the book is here in print.