Gaston Chaissac was a French outsider artist. In his paintings, Chaissac rendered playful, childlike figures with askew grins out of shapes made of vibrant, flat colors outlined in black. The artist termed his style “modern rustic.” Along with paper, he painted on a variety of found materials, including tree stumps, brooms, and rocks. Born into a rural working class family on August 13, 1910 in Avallon, France, the artist taught himself to paint after his neighbors, artists Otto Freundlich and Jeanne Kosnick-Kloss, introduced him to Modern art and encouraged his development. Chaissac participated, along with Jean Dubuffet, in the first Art Brut exhibition in Drouin in 1949. For the remainder of his life, Chaissac continued to study...