Lee Ufan works in series, which evolve over many years. He began his 'Correspondence' paintings in 1991. They consist of single brushstrokes of blue or grey paint of a similar length, on a white ground. The brushstrokes are painted vertically or horizontally, or more usually a combination of both directions. Each brushstroke creates a relationship to the white canvas ground and to other brushstrokes. Lee Ufan mixes his pigments with ground stone, which produces a grainy residue on the surface of the canvas. The artist has written, 'every brushstroke must show the correspondence of living things endowed with rhythm and breathing'.