In her geometric paintings quoting De Stijl and Minimal Art, Mary Heilmann combines the constructive with the expressive, a sober formal language with contrasting, powerful colours. The work "The Red Square" (1978) consists of two square canvases of different sizes that are firmly connected to each other on the reverse side and were originally independent works. Inspired by geometric painting and Colour Field Painting, the work shows nothing but a red square on each canvas, which is placed in a monochrome, beige coloured area, decisively out of the centre. The severity of the monochrome geometry is broken by eccentrically placed red splashes of paint. These, of course, are by no means accidental and deliberately break the minimalist clarity of the works. Heilmann's non-figurative works are characterised not least by their contrasting colours. "The Red Square" is an exemplary work for this, since the intense red of the square forms clearly stands out from the light background. Heilmann's work is in line with the artistic work of Josef Albers, Ad Reinhardt and Kenneth Noland − other important artists of Minimal Art and Color Field Painting, who are also represented in the Städel Museum's collection. At the same time she extends their concept of the picture into space and our present, as the two canvases are screwed together like objects, thus emphasising their objectness.