From the late 1930s to the mid-1940s, Dove's approach became more intellectual and objective as he experimented further with abstraction and with spatial, geometric, and color relationships. Although he still gained initial inspiration from nature and continued to paint in an intuitive manner, he now reduced elements to their simplest forms and either stressed flatness or spatial ambiguity. He de-emphasized the descriptive details, inner energies, or poetry of the subject and focused on the arrangement of forms in space and the selection of colors, an interest made clear by his frequent use of titles such as Pozzuoli Red, Yellow, Blue-Green and Brown, and Red, White and Green. His late works, expressions of pure color and form, anticipated the creations of then-emerging abstract expressionists like Gottlieb and Rothko.
In Flour Mill II, painted during his last months in Geneva, Dove transformed the building into a bold configuration suspended in a non-descriptive space. The off-white background serves as a foil to the earthy greens, rusts, browns, and ochres of the abstraction but maintains a density and opacity—due to the matte surface of the wax emulsion medium—that prevent it from being overpowered by the intensity of the colors. Therefore, the design and its ground are treated as two presences of equal dominance on a flat surface. Duncan Phillips compared this abstract treatment of the subject to a "Chinese character" composed of "square, vibrant brushstrokes."