(1) The shift from silent to sound film at the end of the 1920s marks, so far, the most important transformation in motion picture history. (2) Despite all the highly visible technological developments in theatrical and home delivery of the moving image that have occurred over the decades since then, no single innovation has come close to being regarded as a similar kind of watershed. (3) In nearly every language, however the words are phrased, the most basic division in cinema history lies between films that are mute and films that speak.
