Aided by the French mystic and historian Antonin Gadal, Rahn argued that there was a direct link between Wolfram von Eschenbach's Parzival and the Cathar Grail mystery.
Under indflydelse af den franske mystiker og historiker Antonin Gadal hævdede Rahn, at der var en direkte forbindelse mellem Wolfram von Eschenbachs Parzival og det kathariske gral-mysterium.