The image shows a series of four isometric cube diagrams labeled (1) through (4). Each cube is constructed from a grid of small squares. The squares are shaded in a pattern that appears to represent a musical scale or chord. The letters 'O', 'E', 'A', 'E', 'I', 'O' are written along the bottom of each cube, likely representing the notes of the scale. The shading pattern changes slightly in each cube, suggesting a progression or transformation of the musical structure. The background is a pale yellow, and the image is labeled 'Fig. 56'. The text 'minor' and 'major' are written in the bottom left corner of the first cube.