Leo Braudy is an English professor at the University of Southern California and an expert on celebrity, popular culture of the 1950s, and film history.
 

"The history of theater from the medieval period until the nineteenth century has been in large part a history of further and further separations of the scene of dramatic action from the physical situation of the audience. Even as the subject matter--in the plays of Ibsen, Chekhov, and Strindberg--became more and more continuous with the life of the audience, the stage itself pulled in its apron, emphasized its proscenium, and became a room with an invisible fourth wall, allowing the audience to look in, while keeping it more definitely outside. The progress of film was the reverse. From the stylized and theatrical settings of the early dramas, silent films moved into greater and greater involvement with the actors. Previously the audience saw actors from a distance, with a sense of tableau and formal separation. Although they seemed to be like us, they were not: silent, hieratic, caught in frightened frenzies of comedy, tragedy, and melodrama."

— Leo Braudy