‘I try to organise a field of visual energy which accumulates until it reaches maximum tension’, Riley said of this work. From 1961 to 1964 she worked with the contrast of black and white, occasionally introducing tonal scales of grey. In Fall, a single perpendicular curve is repeated to create a field of varying optical frequencies. Though in the upper part a gentle relaxed swing prevails, the curve is rapidly compressed towards the bottom of the painting. The composition verges on the edge of disintegration without the structure ever breaking.