Goethe was one of the key figures of German literature and the movement of Weimar Classicism in the late 18th and early 19th centuries; this movement coincides with Enlightenment, Sentimentality (Empfindsamkeit), Sturm und Drang and Romanticism. The author of the scientific text Theory of Colours, he influenced Darwin with his focus on plant morphology.^[4][5] He also served at length as the Privy Councilor ("Geheimrat") of the duchy of Weimar.