Structuralism states that culture can be understood as a system of signs and that structuralists believe everything has rules that must be followed. Structuralist film theory emphasizes how films convey meaning through codes and conventions similar to how languages construct meaning. Todorov's theory of narrative consists of equilibrium, disequilibrium, and new equilibrium as different stages of a story. Freud's theory includes the id, ego, and superego and the Oedipus complex. Propp identified eight character types that are commonly repeated in stories.