tore nordenstam explanation and understanding in the history of art

Sometimes Mondrian uses a diamond format instead of the usual rectangular one, as in
the following example:
Fig. 5
Composition No. 1: Lozenge with four lines, 1930
Oil on canvas, diagonal 95 cm
Solomon R. Guggenheim Museum, New York
Against the background of the other pictures, the picture above might be described as
depicting five rectangles, with most of the rectangles outside the picture surface. Other
descriptions are possible. One can e.g. describe it as consisting of four triangles, four
black surfaces, and a more complex area in the middle.
Only the pictures from the last three years of Mondrian’s life (1942-44) break this pattern
which characterizes the paintings from the twenties and the thirties; e.g. the following
two paintings where the black bands have been replaced with coloured stripes (Fig.6 - 7).