Judd disliked the idea of ‘composition’, which for him meant a process of gradually adjusting the design of a work of art until it became aesthetically pleasing. Instead, he created works that develop according to clearly-defined principles, determined in advance. In the late 1960s, he sometimes used elementary mathematical sequences to introduce more complex, asymmetrical patterns into his work. In Untitled 1969, a series of boxes are attached to the wall, horizontally linked by a single square pipe. The increasing size of the boxes is determined by the Fibonacci sequence, so that each one is as large as the two preceding it. The spaces between the boxes are based on the same intervals, but running in the opposite direction. Judd insisted that it wasn’t necessary to understand the mathematics, as long as the viewer can see that there is an underlying order within the piece.
In the mid-1970s, Judd began to make works using wood again. He wanted to make large-scale objects which would define the space of the room in which they were installed. Plywood was cheap and would not bend or buckle, so that he could achieve his customary precision in works built on a larger scale. Untitled 1973, for example, consists of seven square units, each side of which measures 77 inches, with an equal interval between each unit.