 If his stay in London was disappointing professionally, however, it proved a fertile period for Semper's theoretical, creative and academic development.He published "Die vier Elemente der Baukunst" ("The Four Elements of Architecture") in 1851 and "Wissenschaft, Industrie und Kunst" ("Science, Industry and Art") in 1852.These works would ultimately provide the groundwork for his most widely regarded publication, "Der Stil in den technischen und tektonischen Künsten oder Praktische Ästhetik," which was published in two volumes in 1861 and 1863.