“The Cleveland Museum of Art has postponed indefinitely a major international exhibition scheduled for 2006 because other museums sharing the show couldn’t afford terrorism insurance for artworks valued at more than $1 billion. The decision highlights an open secret in the art world: With art prices skyrocketing and insurance premiums rising to meet them, it’s becoming harder for art museums to sustain the flow of blockbusters that have been a fixture of American cultural life for decades.”