“Films must be drawings brought to life”: this was Hermann Warm’s formula at the time that he and his two fellow designers were constructing the CALIGARI world.
In accordance with his beliefs, the canvases and draperies of CALIGARI abounded in complexes of  jagged, sharp-pointed forms strongly reminiscent of gothic patterns. Products of a style which by then had become almost a mannerism, these complexes suggested houses, walls, landscapes. Except for a few slips or concessions — some backgrounds opposed the pictorial convention in too direct a manner, while others all but preserved them — the settings amounted to a perfect transformation of material objects into emotional ornaments. With its oblique chimneys on pell-mell roofs, its windows in the form of arrows or kites and its treelike arabesques that were threats rather than trees, Holstenwall resembled those visions of unheard-of cities which the painter Lyonel Feininger evoked through his edgy, crystalline compositions.
In addition, the ornamental system in CALIGARI expanded through space, annuling its conventional aspect by means of painted shadows in disharmony with the lighting effects, and zigzag delineations designed to efface all rules of perspective. Space now dwindled to a flat plane, now augmented its dimensions to become what one writer called a “stereoscopic universe.”
Lettering was introduced as an essential element of the settings — appropriately enough, considering the close relationship between lettering and drawing. In one scene the mad psychiatrist’s desire to imitate Caligari materializes in jittery characters composing the words “I must become Caligari” — words that loom before his eyes on the road, in the clouds, in the treetops.
The incorporation of human beings and their movements into the texture of these surroundings was tremendously difficult. Of all the players only the two protagonists seemed actually to be created by a draftman’s imagination.
Werner Krauss as Caligari had the appearance of a phantom magician himself weaving the lines and shades through which he  paced, and when Conrad Veidt’s Cesare prowled along a wall, it was as if the wall had exuded him. The figure of an old dwarf and the crowd’s antiquated costumes helped to remove the throng on the fair’s tent-street from reality and make it share the bizarre life of abstract forms.
If Decla had chosen to leave the original story of Mayer and Janowitz as it was, these “drawings brought to life” would have told it perfectly. As expressionist abstractions they were animated by the same revolutionary spirit that impelled the two scriptwriters to accuse authority — the kind of authority revered in Germany — of inhuman excesses. However, Wiene’s version disavowed this revolutionary meaning of expressionist staging, or, at least, put it, like the original story itself, in brackets. In the film CALIGARI expressionism seems to be nothing more than the adequate translation of a madman’s fantasy into pictorial terms.
This was how many contemporary German reviewers understood, and relished, the settings and gestures. One of the critics stated with self-assured ignorance: “The idea of rendering the notions of sick brains … through expressionist pictures is not only well conceived but also well realized. Here this style has a right to exist, proves an outcome of solid logic.”