Unlike video and cinema (although sometimes employing elements of both), the theater is a living, real-time event, with both performers and audience mutually interacting, each aware of the other's immediate presence. This turns out to be an extremely important distinction. Distinguished film stars, particularly those with theater backgrounds (as most have), routinely return to the live dramatic stage – despite the substantially greater financial rewards of film work – and invariably prefer stage acting because of the immediate audience response theater provides, with its corresponding sensations of excitement and presence. The first of these is the rapport existing between actor and audience. Both are breathing the same air, both are involved – at the same time and in the same space – with the stage life depicted by the play. Sometimes their mutual fascination is almost palpable; every actor's performance is affected by the way the audience yields or withholds its responses: its laughter, sighs, applause, gasps, silences. Live theatrical performance is always a two-way communication between stage and house.   Second, theater creates a relationship among the audience members. Having arrived at the theaters as individuals or in groups of two or three, the audience members quickly find themselves fused into a common experience with total strangers: laughing at the same jokes, empathizing with the same characters, experiencing the same revelations. This broad communal response is never developed by television drama, which is played chiefly to solitary or clustered viewers who (because of frequent commercial advertisements) are only intermittently engaged, nor is it likely to happen in movie houses, where audience members essentially assume a one-on-one relationship with the screen and rarely (except in private or group screenings) break out in a powerful collective response, much less applause. By contrast, live theatrical presentations generate audience activity that is broadly social in nature: the crowd arrives at the theater at about the same time, people mingle and chat during intermissions, and all depart together, often in spirited conversation about the play. Moreover, they communicate during the play: laughter and applause build upon themselves and gain strength from the recognition that others are laughing and applauding. The final ovation – unique to live performance – inevitably involves the audience applauding itself, as well as the performers, for understanding and appreciating the theatrical excellence they have all seen together. And plays with political themes can even generate collective political response. In a celebrated example, 1935's Waiting for Lefty was staged as if the audience were a group of union members; by the play's end the audience was yelling "Strike! Strike!" in response to the play's issues. Obviously, only a live performance could evoke such a response. Finally, live performance inevitably has the quality of immediacy. The action of the play is taking place right now, as it is being watched, and anything can happen. Although in most professional productions the changes that occur in performance from one night to another are so subtle that only an expert would notice, the fact is that each night's presentation is unique, and everyone present – the audience, the cast, and those behind the scenes – knows it. This awareness lends an excitement that cannot be achieved by theatrical events that are wholly in the can. One reason for the excitement, of course, is that in live performance, mistakes can happen; this possibility occasions a certain abiding tension, perhaps even an edge of stage fright, which some people say creates the ultimate thrill of the theater. But just as disaster can come without warning, so too can splendor. On any given night, each actor is trying to better his or her previous performance, and no one knows when this collective effort will coalesce into something sublime. The actors' constant striving toward self-transcendence gives the theater a vitality that is missing from performances fixed unalterably on videotape or celluloid. But perhaps most appropriately, the immediacy of live performance embodies the fundamental uncertainty of life. One prime function of theater is to address the uncertainties of human existence, and the very format of live performance presents a moment-to-moment uncertainty right before our eyes. Ultimately, this immediate theater helps us define the questions and confusions of our lives and lets us grapple, in the present, with their implications.