The Golden Section is a spiral growth pattern found in nature--in the swirl of seashells, the arrangement of flower petals, and the staggering of pinecone scales. It’s based on Fibonacci’s law, a numerical series in which each new number is the sum of the prior two. When expressed geometrically, ever-larger spirals spread outward from the center in a manner similar to the motif I’ve used for this sweater.

--description from Loop-d-Loop, pgs. 134 154 (pattern on pg. 154)

Circular needle helps with flexibility, but is not necessary.