In the 1820s, Wilhelm von Humboldt observed that human language was a rule-governed system, anticipating a theme that was to become central in the formal work on syntax and semantics of language in the 20th century. Of this observation he said that it allowed language to make "infinite use of finite means" ("Über den Dualis", 1827). Humboldt's work is associated with the movement of Romantic linguistics, which was inspired by "Naturphilosophie" and Romantic science. Other notable representatives of the movement include Friedrich Schlegel and Franz Bopp.