In 1843 , he joined a literary club in Berlin called Tunnel über der Spree ( Tunnel over the river Spree ) where he came into contact with many of the most renowned German writers including Theodor Storm , Joseph von Eichendorff and Gottfried Keller .
In 1843 , he joined a literary club called Tunnel über der Spree ( i.e. Tunnel over the river Spree ) in Berlin where he came into contact with many of the most important German writers such as Theodor Storm , Joseph von Eichendorff and Gottfried Keller .