Das war der Seelen wunderliches Bergwerk.
Wie stille Silbererze gingen sie
als Adern durch sein Dunkel. Zwischen Wurzeln
entsprang das Blut, das fortgeht zu den Menschen,
und schwer wie Porphyr sah es aus im Dunkel.
Sonst war nichts Rotes.

— Rainer Maria Rilke,Orpheus. Eurydike. Hermes. 1904

An enigma, like a riddle is proposed to the subject by another subject. But the solution of a riddle in theory is theoretically completely in the conscious possession of the one who poses it, and thus, it is entirely resolved by the answer. An enigma, on the contrary, can only be proposed by someone who does not master the answer, because his message is a compromise formation in which his unconsciousness takes part. 

— Jean Laplanche, Essays on Otherness(cited from Photography&Surrealism)