Wall began making large backlit transparencies in the late 1970s. He had experimented with filmmaking, and he felt that staging scenes for the camera could radically broaden the potential of still photography. Another touchstone for his large pictures has been the grand theater of human figures in Western painting since the Renaissance.
Wall's ambitious project began to take shape in the early 1980s when he embarked on a series of photographs devoted to the everyday lives of people at the margins of society. Many of the pictures (including Milk) were derived from incidents that Wall observed and subsequently adapted and restaged with nonprofessional actors.
In Milk the harsh, impersonal geometry of the background transforms the scene into a stage, and the man's clenched posture and the liquid explosion distill the violence of anger into a vivid symbol. Instead of evoking the continuity of experience, the arrested image snatches the figure out of time altogether, rendering him a static emblem of distress.
from The Museum of Modern Art, MoMA Highlights since 1980, New York: The Museum of Modern Art, 2007, p. 57