What is the theme of The Cabinet of Dr Caligari?

The theme of The Cabinet of Dr. Caligari revolves around the nature of authority and the fragility of reality. It explores the manipulation of perception and the psychological effects of authoritarian control, as represented by Dr. Caligari's somnambulist, Cesare. The film also delves into madness and the thin line between sanity and insanity, ultimately questioning the reliability of the narrator's perspective. Through its expressionist style, it reflects the anxieties of post-World War I Germany.