Using inexpensive, standard-sized fluorescent lamps, fixtures and wiring, Dan Flavin fills large rooms with tremendous energy. Some of the 50 objects and installations on view at the Museum of Contemporary Art’s current retrospective are unbearably intense, some are seductive, and some are antagonistic. Radical in conception and execution, the light pieces hover between sculpture and drawing. Indeed, in many cases Flavin thinks like a draftsman -- its just that his lines are not marks, but three-dimensional shapes in space that radiate light and color; they exist only so long as his characteristic fluorescent lamps function and receive electric power. These lines are most effective when they have an entire space to command and can stake their claim to it by their reflections on the floor, walls and ceiling.