A tribute to a courageous woman, as well as the unspoiled beauty of her surroundings, “Christina’s World” is Andrew Wyeth’s most famous painting. A representational watercolorist whose neutral-toned, nuanced work depicted rural America’s rustic beauty, Wyeth painted “Christina’s World” in homage to his neighbor, Christina Olson, who was dragging herself toward her house despite crippling polio. Wyeth, moved by her determination, painted her and her house in numerous works.