One of the recurring elements or motifs in Theodor Fontane's novel Effi Briest is that of the Chinaman. The Chinaman is a source of fear for Effi, something like a phantom. References to him are particularly frequent in chapters 6–22 and appear absent in chapters 28–36. The motif is used too frequently to be easily dismissed as unimportant. Its appearance is also "inconvenient" when considering the period or genre the novel belongs to: Fontane's novels are considered examples of "realism", and realism tends to avoid supernatural elements.
In spite of having answered several questions about Effi Briest on this site, I still don't know what the novel wants to achieve with the motif of the Chinaman. Is it possible to make sense of this motif in this realist novel?