Louis Kahn (1901–1974), Sketch for a mural, 1951 – 1953. Ink on paper, 298 × 400 mm.
I gave myself an assignment: to draw a picture that demonstrates light. Now if you give yourself such an assignment, the first thing you do is escape somewhere, because it is impossible to do. You say the white piece of paper is the illustration; what else is there to do? But when I put a stroke of ink on the paper, I realised that the black was where the light was not, and then I could really make a drawing, because I could be discerning as to where the light was not, which was where I put the black. Then the picture became absolutely luminous.
— Louis Kahn