Courbet painted events and scenery primarily from his native Ornans, a village in the remote Franche-Comté region. A proponent of realism, he challenged traditional ideas about art by depicting simple peasants and rustic scenery with dignity and on the grand scale usually reserved for history paintings.
Overhanging trees and lush green undergrowth surround a narrow waterway in the forest interior shown in The Stream. The primitive site, seemingly undisturbed by civilization, evokes a yearning popular during the nineteenth century, a romantic desire for a peaceful, restorative retreat from the rigors of modern life. Courbet used an unorthodox palette knife technique to apply irregular layers of pigments, creating a roughly worked surface imitating the textures of foliage, water, and chalky rocks to evoke the physical presence of the terrain.
When he exhibited this painting at the Exposition Universelle in 1855, Courbet specifically identified the wooded gorge in The Stream as Le ruisseau du Puits-noir, vallee de la Loue (Stream of the Black Well, Valley of the Loue), a famous site near Ornans. Long interested in the natural history of his region, including its geology, Courbet was scrupulously accurate in depicting the setting. Freshly observed details and subtle paint manipulation place the National Gallery painting as the first of several depictions of the site.
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