Victor Vasarely. Study for Deuton RB. 1966. Gouache on paper, 9 7/8 × 9 7/8ʺ (25.1 × 25.1 cm). Gift of Mrs. Lily Auchincloss. © 2016 Artists Rights Society (ARS), New York / ADAGP, Paris

Rarely seen drawings whose optical effects, graphic punch, and challenging subject matter represent the flip side of the period’s prevalent abstraction.