Piet Mondrian (1872–1944) stopped working with anything but the primary colours red, yellow and blue and the non-colours grey, white and black in 1934. He used right angles and the principle of “constant ratio” in his compositions to construct asymmetrical grids of vertical and horizontal lines cadenced by rectangular planes of different shapes and sizes. Pushed back towards the edges, the planes of colour seem to draw the eye towards a space extending beyond the painting itself. Despite this, rigorous composition emphasizes the flatness of the work and asserts its reality: “Only pure relations between pure constructive elements can lead to pure beauty”.