The spell wore off quickly. At the time of Péladan’s death, in 1918, he was already seen as an absurd relic of a receding age. He is now known mainly to scholars of Symbolism, connoisseurs of the occult, and devotees of the music of Erik Satie. (I first encountered Péladan in connection with Satie’s unearthly 1891 score “Le Fils des Étoiles,” or “The Son of the Stars”; it was written for Péladan’s play of that title, which is set in Chaldea in 3500 B.C.) His contemporary Joris-Karl Huysmans remains a cult figure—“Against the Grain,” Huysmans’s 1884 novel, is still read as a primer of the Decadent aesthetic—but none of Péladan’s novels have been translated into English. So when an exhibition entitled “Mystical Symbolism: The Salon de la Rose + Croix in Paris, 1892-1897” opens at the Guggenheim Museum, on June 30th, most visitors will be entering unknown territory. The show occupies one of the tower galleries, in rooms painted oxblood red, with furniture of midnight-blue velvet. On the walls, the Holy Grail glows, demonic angels hover, women radiate saintliness or lust. The dark kitsch of the fin de siècle beckons.