“My icons do not raise up the blessed savior in elaborate cathedrals,” the artist Dan Flavin once said. “They are constructed concentrations celebrating barren rooms. They bring a limited light.” Flavin made art out of long fluorescent bulbs, installations that he liked to call “situations.” The light he creates sometimes has color, sometimes not. It is both intense and diffuse. In the spring of 1976, Flavin had a breakout moment. His work was on view at Leo Castelli Gallery in New York and at Galerie Heiner Friedrich in Cologne, winning praise across Europe and the U.S. This exhibition, which inhabits two floors, recreates those shows in one location. The full spectrum of colors that make up Flavin’s visual vocabulary—red, pink, green, blue, yellow, cool white, daylight, warm white, and soft white—are all here. —E.C.