"It was as if a whirlwind had roared through the gallery, rattling the windows and shattering the glass." In 1882, five years after Gustave Courbet’s death, his friend Jules-Antoine Castagnary compared his paintings to a force of nature, taking Paris by storm. It was a fitting image for a realist, and indeed Courbet had anticipated it in his art, as great artists do. The painting was a landscape done at the height of his powers, "Le Coup de Vent," that is, "The Gust of Wind."

Courbet set his scene in the depths of a rocky, wild forest. Across the sky the streaks of darkening clouds warn of an approaching squall. The rising winds begin to sway the trees along the rim of an abandoned quarry that is now a pond. Suddenly, a violent gust strikes an oak that stands out in front of the others, nearest to us. Its leafy branches bend over backwards, but the trunk holds its ground, though barely.

"He casts off the rules of art as a madman does his clothes" was a 19th-century critic’s complaint about Tintoretto—Courbet came in for worse. But the Impressionists would gaze in awe at the impetuosity and control of his rugged canvases, the pigments scraped and dragged with a palette knife and brushes and then rubbed smooth with rags. A Courbet landscape like "The Gust of Wind" has a physicality so tangible we can run our fingers across the stones, breathe the air, smell the rain. Paul Cézanne, who had no fear of painting thickly, spoke of Courbet as a "builder."
 
Courbet was a realist who studied nature, the Old Masters, and even his contemporaries and saw no contradiction. As soon as the 22-year-old Courbet arrived in Paris, he went out to the forest of Fontainebleau, 20 miles outside the city. It was 1841, and J.-B.-C. Corot, the dean of the Barbizon painters, had been working there for two decades. Corot and Théodore Rousseau were not realists per se, but painting sketches every day in the woods made their landscapes the most natural yet. Once the hunting ground of kings, Fontainebleau was and is a favorite excursion spot for Parisians seeking to immerse themselves in nature. Small wonder that after Corot’s discovery, it became a mecca for painters, as well.

"Beauty is found in Nature under the most varied aspects," he wrote to young artists, planting his foot squarely on the academy’s back and then giving a push, "and its beauty is superior to all artistic conventions." Beauty, of course, is in the eye of the beholder: Corot populated the misty woods with nymphs and honest peasants; Rousseau imbued his twilight with a romantic tinge. Not a little influenced by photography, Courbet pushed beyond his peers to embrace the visual overload of a forest floor choked with roots and undergrowth. His earliest views of Fontainebleau are richly painted snapshots inside thickets. Like a photographer, he was banking on the authenticity of randomness, what one critic, Champfleury, called the "genius of the absence of composition."

"The Gust of Wind," painted about 20 years later, contains so many exceptions to his usual rules that it represents a kind of marvelous enigma. It is Courbet’s largest pure landscape, not including a single figure or any wildlife. It is artfully composed. The giant oak connects the compelling diagonals of the sky and the stony embankment, while indicating the line of trees that lead into the distance. Its colors are limited to the essentials: ochre, green and blue, with hardly a touch of his signature russet. Finally, though, there’s something else, far more important. While providing every Fontainebleau feature—from the pool to the tawny, jagged rocks—Courbet was at pains to emphasize that the view was his own invention. The distant mountains are the main disclaimer. Courbet came from the mountains of the Franche-Comté region; there aren’t any around Paris. Considered together with the orchestration of every element to focus our attention on a single tree under stress, "The Gust of Wind" owes less to real life than to the Dutch landscapes of Jacob van Ruisdael, who used shattered trees as evocations of Man’s Fate, as another Frenchman once put it. In light of the controversies assailing him at the time, Courbet’s theme, one suspects, is "I’m still standing."