From the Heilbrunn Timeline of Art History:
Near the end of Wagner’s second opera of the Ring cycle, Die Walküre (The Valkyrie), the Valkyrie Brünnhilde, having attempted to help the sibling lovers Siegmund and Sieglinde against their fathers’ wishes, is punished for her betrayal. Wotan puts her to sleep and surrounds her with a ring of fire (she will be awakened in turn by her nephew Siegfried, the incestuous son of Siegmund and Sieglinde, in the third opera of the cycle).
Kiefer portrays the dormant Brünnhilde as French actress Catherine Deneuve in François Truffaut’s film Mississippi Mermaid, using a photograph he snapped in a movie house in 1969. In the film, Deneuve plays a deceitful mail-order bride who comes to the island of Réunion to marry a plantation owner, played by Jean-Paul Belmondo. Aside from the parallels of love and betrayal in both the Ring Cycle and Truffaut’s film, Kiefer thought the choice of Deneuve for Brünnhilde both ironic and amusing: she was for him “the contrary of Brünnhilde. Very slim, very French, very cool, very sexy,” hinting that no man would go through fire to obtain Wagner’s corpulent, armored Valkyrie.