Here is a rare chance to see six decades of work by the abstract painter Thornton Willis, who is now 85. Spanning the years 1967 to 2017, the exhibition looks at Willis’s most important series: Slats, Wedges, Zig-Zags, Triangles, Prismatics, Lattices, Cityscapes, and Steps. The show’s arc is chronological, which allows viewers to see how each artistic experiment flowed into the next. “The best painting is always ‘open-ended,’” says Willis. “Paintings that aim for resolution lack a dynamic. Open-ended work asks questions, and partners with the viewer to bring the experience to closure.” —Clara Molot