Montage theory
With llustrations from Sergei Eisenstein's Battleship Potemkin
and Dziga Vertov's The Man with the Movie Camera

The pioneering Russian film director and theorist Sergei Eisenstein believed that montage (juxtaposing images by film editing) could create ideas or have an impact not found in the individual images. Two or more images together create a "tertium quid" (third thing) that makes the whole greater than the sum of its individual images. Montage was thus a powerful ideological device that could be used to educate or to arouse the audience.

Below are two sets of images from the end of the "Odessa Steps" sequence of Eisenstein's Battleship Potemkin (1925). In the first, the rapid montage of the three cherubs makes the small angel seem to be throwing a punch. In the second sequence, three shots of stone lions, shown rapidly in succession, indicate awakening militancy. Both montages appear at the point in Potemkin when the people fight back against oppression.
The images below are from Vertov's The Man with a Movie Camera (1929). The first pair is an example of a graphic match: two images unnrelated except for visual similarity. The second and third pairs are examples of using montage for thematic contrasts, in these cases a comparison of frivolous vs. productive activities. (Notice that filmmaking, as represented by the hands of the film editor, is included among productive activities.)

Above: In The Man with the Movie Camera, Vertov includes a visual joke referring to famous experiments in montage carried out by the Russian filmmaker Lev Kuleshov. Kuleshov intercut shots of the expressionless face of an actor with various other shots such as soup, a coffin, and a pretty girl. He discovered that the film audience interpreted the actor's single expression as hungry, sad, happy, etc., according to the images with which it was associated. This became known as the "Kuleshov effect," an important contribution to montage theory.
Vertov includes shots of store dummies in his film as a humorous tribute to the Kuleshov effect.