The hemispheres along the bar of Eva Hesse’s Addendum are positioned at increasing intervals determined by a fixed mathematical series. Many artists used serial systems at this time because they provided a way of composing sculptures without recourse to personal expression. Hesse hung rope cords from each hemisphere which fall to the ground in unpredictable curls. The regulated structure of the bar contrasts with the disordered appearance of the cords. But Hesse recognised that such systems were hardly rational, commenting that ‘Serial art is another way of repeating absurdity’.