Before indicating the different ways in which information is encoded in digital storage media, the term „format“ indicated the different formats developed for shooting or viewing motion pictures. The history of the medium of film is also the history of the different film formats and of the different projection aspect ratios. In 1930, while he was traveling across the United States before moving to Mexico in order to work on the unfinished project of Que viva Mexico!, Eisenstein gave a lecture entitled The Dynamic Square at the Academy of Motion Picture Arts and Sciences in Hollywood. In it, he defends the idea of a dynamic format for film projections which is closely connected to his understanding of the nature of the medium of cinema and of its historical transformations. Based on a process, the process of montage, whose traces can be found across the entire history of the arts, cinema was never for Eisenstein a stable medium rooted in some kind of medium specificity. The dynamic format that he praises in The Dynamic Square, is nothing else than a description of cinema’s own dynamic, unstable nature.