From wiki page - The woman in the painting is Anna Christina Olson (May 3, 1893 – January 27, 1968). Anna had a degenerative muscular disorder, Charcot–Marie–Tooth disease, which meant that she had not been able to walk since she was a young child. She was firmly against using a wheelchair and so she would crawl everywhere. Wyeth was inspired to create the painting when he saw her crawling across a field while he was watching from a window in the house. He had a summer home in the area and was on friendly terms with Olson, using her and her younger brother as the subjects of paintings from 1940 to 1968. Olson was the inspiration and subject of the painting, but she was not the primary model; Wyeth’s wife Betsy posed as the torso of the painting. Olson was 55 at the time that Wyeth created the work.