of glass forms a rhomboid, close to the center of the painting and recalling, with slight distortion, the shape of the entire canvas, and framing much of the action.
The back window serves as a background for all three customers, but not for the server. Its variance from the shape of the painting as a whole also hides a curious symmetry that would otherwise be obvious: The head of the customer who is sitting alone is at the precise center of the frame-within-a-frame (which is also the exact center of the painting as a whole). Although they sit around a bend in the counter, the heads of the couple are directly to his right, so that a horizontal line, drawn precisely halfway between the top and the bottom of the canvas, would bisect all three heads. The entire human element in the painting is therefore contained within the lower right-hand quarter of the canvas.
As Jo Hopper's journal entry notes, the brightest spot in the painting is the bit of bright ceiling close to the hidden fluorescent light that illuminates the interior. The ceiling is obviously of limited relevance to any narrative that might be unfolding among the customers below; this is Hopper's realism at work.
Outside the diner, dull colors predominate, as might be expected at night. Inside, the counter-top and the men's suits are also dull. The two brightly-colored spots in the entire interior are the white outfit worn by the server and the female customer's red blouse. Indeed, her red blouse and lipstick represent the only use of red in the entire composition, causing her to stand apart from everything else in the painting.
Hopper had a lifelong interest in capturing the effect of light on the objects it touched. This interest extended to his numerous canvases of sunlit houses and lighthouses in New England, but he was equally intrigued by the nighttime effect of artificial, manmade light spilling out of windows, doorways and porches, dealing with the subject over and over again in paintings like Drug Store (1927), Gas (1940), Rooms for Tourists (1945) and Summer Evening (1947).
However, Nighthawks was probably Hopper's most ambitious essay in capturing the night-time effects of manmade light.
For one thing, the diner's plate-glass windows cause far more light to spill out onto the sidewalk and the brownstones on the far side of the street than is true in any of his other paintings. As well, this interior light comes from more than a single lightbulb, with the result that multiple shadows are cast, and some spots are brighter than others as a consequence of being lit from more than one angle. Across the street, the line of shadow caused by the upper edge of the diner window is clearly visible towards the top of the painting. These windows, and the ones below them as well, are partly lit by an unseen streetlight, which projects its own mix of light and shadow. As a final note, the bright interior light causes some of the surfaces within the diner to be reflective. This is clearest in the case of the right-hand edge of the rear window, which reflects a vertical yellow band of interior wall, but fainter reflections can also be made out, in the counter-top, of three of the diner's occupants. None of these reflections would be visible in
daylight.