What was this? Limbo, hell, a disco gone out of control, or just a little taunt directed at elaborate installation art? Not necessarily any of these. A torture chamber or purgatory—purgatory as a space of purification? Who can say for sure? After all, what is seen “is never found in what is said,” as Michel Foucault once put it. Still, I have to try to describe this installation, Mamaterial, 2006, by Ralf Ziervogel, a former student of Lothar Baumgarten at Universität der Künste in Berlin and one of the most promising young artists around. The installation (based on the artist’s graduate project)