greens crossing greens (to Piet Mondrian who lacked green) - Dan Flavin, 1966
From the Guggenheim:
Employing only commercial fluorescent lights in his work, Dan Flavin devised a radical new art form that circumvented the limits imposed by frames, pedestals, or other conventional means of display. His embrace of the unadorned fluorescent fixture as an aesthetic object placed him at the forefront of a generation of artists whose use of industrial materials, emphasis on elementary forms, and nonhierarchical relationships among component parts became the salient characteristics of Minimalism.