taffan Ahrenberg’s acquisition of Cahiers d’Art a few years ago was a nostalgic purchase. Ahrenberg, the scion of a prominent Swedish collecting family, had his memory jogged on a walk past the publication’s offices at 14 rue du Dragon in Paris, recalling its founder’s name, Christian Zervos, amid the spines of his father’s library. Zervos, who founded the publication in 1926 and ran it through 1960 (with a brief interruption during WWII), is best known for his Picasso catalogue raisonné, widely held to be the most comprehensive of its kind.