Jean Paul's Titan was followed by Flegeljahre ("The Awkward Age", 1804-5). His later imaginative works were Dr Katzenbergers Badereise ("Dr Katzenberger's Trip to the Medicinal Springs", 1809), Des Feldpredigers Schmelzle Reise nach Flätz ("Army Chaplain Schmelzle's Voyage to Flätz", 1809), Leben Fibels ("Life of Fibel", 1812), and Der Komet, oder Nikolaus Marggraf ("The Comet, or, Nikolaus Markgraf", 1820–22). In Vorschule der Aesthetik ("Introduction to Aesthetics", 1804) he expounded his ideas on art; he discussed the principles of education in Levana, oder Erziehungslehre ("Levana, or, Pedagogy", 1807); and the opinions suggested by current events he set forth in Friedenspredigt ("Peace Sermon", 1808), Dämmerungen für Deutschland ("Twilights for Germany", 1809), Mars und Phöbus Thronwechsel im Jahre 1814 ("Mars and Phoebus Exchange Thrones in the Year 1814", 1814), and Politische Fastenpredigten ("Political Lenten Sermons", 1817). In his last years he began Wahrheit aus Jean Pauls Leben ("The Truth from Jean Paul's Life"), to which additions from his papers and other sources were made after his death by C. Otto and E. Förster.