The duality of his nature is frequently reflected in some of his characters--Cardillac the goldsmith in Mademoiselle de Scudéry and Nathaniel in The Sandman, for example. Cardillac is a virtuous, industrious man by day but a violent criminal at night, while Nathaniel, obsessed by a childhood fantasy, is driven to madness and cruelty.

These tales can be read on several levels: as an expression of the concerns of the Romantic era, as impressive examples of German Romantic literature and as exciting works of fiction made all the more extraordinary by their concern with the supernatural and the bizarre.