When a Bern museum inherited a spectacular collection of around 1,600 works of art, including works by masters such as Monet, Gauguin and Picasso, it spent seven months considering whether to accept the offer. The collection, donated to the Kunstmuseum in 2014 by Cornelius Gurlitt, whose father Hildebrand Gurlitt worked as an art dealer for the Nazis, also included works looted from Jewish property during World War II. A new exhibition, “Taking Stock. Gurlitt in Retrospect,” explores the museum’s journey in researching the provenance of the pieces and the challenges of determining its commitments in the face of Gurlitt’s tumultuous...