James Turrell's Acton at the Indianapolis Museum of Art

Consider the case of James Turrell's "Trace Elements: Light Into Space." The original sculpture, acquired by the Denver Art Museum in 1994, exerted a profound effect on viewers. Several described a "magical" burst of deeply saturated blue light that kicked in after they gazed at the work for 20 minutes. In July 2006, Turrell's assistant reinstalled "Trace Elements," substituting a different brand of light bulbs because the originals were no longer manufactured.

Dissatisfied museum administrators summoned Turrell to "tune" the sculpture himself, but the artist's tweaking failed to re-create the original experience for then-curator Dianne Vanderlip. Intent on witnessing the vivid hues she remembered, Vanderlip organized a third reinstallation in January 2007, followed by a fourth last July with Getty Research Institute's Andrew Perchuk lending a hand.

After all the tweaking, David Turnbull, assistant conservator at the Denver Art Museum, says "Trace Elements" version 2.0 came "close" to approximating the original. "I would say that memories are more intense than the actual event."

The light sculpture now sits in storage.