English: Rosa Bonheur takes more than three years to design her masterpiece (the horse market); already, during her stay in the Pyrenees in 1850, she "thinks a lot about her large painting, I think she will succeed, it occupies her very seriously". Giving preeminence to drawing, she multiplies studies in pencil or charcoal: staging research, then studies of movements and details. She pays particular attention to the study of the characters in terms of their posture and their gestures.