Subtle threads connect a pair of pioneering artists in Converging Lines: Eva Hesse and Sol LeWitt, Sept. 12 to Jan. 10 at the Addison Gallery of American Art on the Phillips Academy campus in Andover, Massachusetts. Throughout the 1960s, their platonic bond strengthened amid a tightknit circle in Lower Manhattan who debated tactics to reinvigorate the process of painting and sculpting. LeWitt devised rigid principles for his systematic placement of smooth geometric shapes, while Hesse turned to new industrial compounds like latex and fiberglass, molding raw materials to suggest the human body. At times she contained and contrasted those organic forms with boxy structures more typical of LeWitt, and he eventually embraced her curves. The wiggly lines LeWitt first drew in 1970, as a tribute to Hesse days after her death at 34 from a brain tumor, loosened over the following four decades into the unruly Scribbles of his final years. Both estates have loaned artworks and postcards they exchanged, punctuated with LeWitt’s legendary 1965 letter that encouraged Hesse—and countless creators since—to persevere at a critical crossroads. This oft-quoted message underscores the importance of mutual support and intellectual discourse among peers.