The impressionist style developed as a method to render more accurately the appearance of the natural world, and was principally a technique for landscape painting. Corot, whose career began in the late 1820s when the academic tradition of landscape painting was being revived, was one of the most prolific and influential exponents of the genre. Forest of Fontainebleau, painted for and exhibited at the Salon of 1834, is a historic landscape, the hybrid category devised to elevate the status of landscape painting by combining with it the subjects of history painting. Although Corot's principal subject here was landscape, contemporaries readily identified the reclining woman in the foreground as Mary Magdalene. Her unbound hair and peasant costume, the deer in the background, and her solitude in the wilderness are traditional attributes of the saint.
In accord with academic training, Forest of Fontainebleau was created in the studio on the basis of sketches and studies that had been painted outdoors. The artist's humble attitude toward nature, unostentatious compositions, responsive paint handling, and conscientious clarity and freshness of vision distinguish his work from the formulaic landscapes of academic contemporaries. Corot declined to participate in the first impressionist exhibition, but his pervasive influence was manifest in works by pupils and followers including Pissarro, Morisot, Renoir, Monet, and Sisley.
More information on this painting can be found in the Gallery publication French Paintings of the Nineteenth Century, Part I: Before Impressionism, which is available as a free PDF https://www.nga.gov/content/dam/ngaweb/research/publications/pdfs/french-paintings-nineteenth-century.pdf