Poet, born in Ehrenbreitstein, WC Germany, the uncle of Franz and Lujo Brentano. He became a Roman Catholic in 1818 and withdrew to the monastery of Dülmen, near Münster (1818–24), where he recorded the revelations of the nun Anna Katharina Emmerich. One of the founders of the Heidelberg Romantic school, he was mostly successful in his novellas, particularly in the Geschichte vom braven Kasperl und dem schönen Annerl (1817, The Story of Just Caspar and Fair Annie), and with his brother-in-law Achim von Arnim he edited Des Knaben Wunderhorn (1805–8), a collection of folk songs that was of seminal influence in the Romantic movement in Europe.