On a formal level, one could say that this painting by Vermeer produces its effect through a fairly complete range of elements: colour, light and composition, leaving aside the subject matter (although this of course has its importance, as well as its multiple interpretations, about which some art historians have elaborated). I will try to look just at the formal aspects in this article.
The juxtaposition of two complementary colours, blue and yellow, provide the colour theme for this painting and produce, in this instance, a feel of tranquility while seeming lively enough. One doesn't go to sleep in front of this painting and this is largely ensured by the play between blue and yellow. The tranquility is more probably induced by the subject matter, and by the sculptural effect produced by the side lighting: a technique regularly used by Vermeer.
Yet combining the complementary colours blue and yellow (or orange) is not sufficient to engender a mood of tranquility, as is illustrated in this contemporary painting by Peter Doig. The strange, hermit-like bearded figure in the canoe (apparently inspired by an album cover of the Allman Brothers, this being Greg Allman, I think, or was it Duane?) is echoed and given added strangeness by the slightly foreboding Alcatraz-like island on the horizon. So, even if we try, we cannot really separate subject matter from formal aspects.
Yet the formal aspects of this painting are very striking. Take the strong horizontal layering of the composition. Here is another work that uses this type of structure:
In this well-know painting by Monet, the gate on which the magpie is perched is the only thing which prevents the painting from being totally divided on a horizontal basis. An echo to this horizontal dynamic is provided by the house. Another striking formal element is the use of colour to produce the effect of white, and the ensuing use of white to show how profound the effects of minimal colour variations can be. There is apparently little colour variation used in this painting, but just look at the warm feeling given off by the rendering on the wall of the house. If one removed this colour from this painting and put it in another context, its relative value would be totally altered, and one could even make it appear "cool" rather than "warm" in some instances. This fine-tuning of the relativity of colour perception is one of the major achivements of the Impressionist movement, and of Monet in particular.
But what happens to colour when things get really hot?
This interior by Matisse is a good example. Interestingly he uses several of the elements that we saw in the Vermeer painting of the milkmaid: an interior, with a window on the left, and a maid performing household tasks involving food at a table which also includes "still life" subjects. But the treatment, and the ensuing mood of the painting, are both very different. Despite the window, there is no lateral lighting here to shape the forms. Everything is treated as a series of flat, brightly coloured shapes, as if they had been cut out of paper. Indeed Matisse used cut-out paper in other works. Not having lighting to conduct the eye over the composition, Matisse relies in just two elements: colour and shape. And the strength of the colours, including a full range of primary and secondary colours used quite purely, induces great warmth. The only impression of depth is provided by the green and blue seen through the window, but one wonders how much of that is induced by the fact that one knows it is a window and that therefore there is greater distance involved. Matisse is questioning our habits of looking, and how we preconcieve and therefore limit what we perceive.
This painting from the 1960's by the American painter R.B. Kitaj uses something of Matisse's approach to colour, well on the way to abstraction, combined with a dose of the kind of realism used by Vermeer in this portrayal of a couple of architects. The colours are less saturated than in the Matisse painting, and the portraits are juxtaposed with what is otherwise an abstract composition, in reference to the use of geometrical shapes in architecture. So we are inevitably drawn back to the subject matter.
Maybe we should conclude that suject and form are inseparable in the creation of mood?