" Fauvism" owes its name to the critic Louis Vauxcelles who, wishing to characterise the audacity of certain paintings displayed at the 1905 Salon d'automne, called the room where they were grouped a "cage aux fauves" (a wild-beast cage). The term "Fauve" is applied to several painters active during the first half of the 20th century (Matisse, Friesz, Derain, Rouault, Dufy, Marquet, Vlaminck, Camoin, Puy, Manguin) who reacted against the analytical methods of Impressionism; they often ringed objects in black and juxtaposed pure tones. They substituted intellectual naturalism (yellow sky, red trees) for visual naturalism. They were of course rebelling against the academic realism taught them by their professors (with the exception of Gustave Moreau). As Matisse wrote: "The expressive aspect of colour imposes itself upon me purely by instinct." Thus we encounter once again, now revolving around the all-importance of colour, Gauguin's Pont-Aven theories on colour composition and the fundamentally subjective nature of the act of painting, as well as the consequences deriving from his ideas: simplification of means, rejection of perspective, chiaroscuro, shading-off, relief and broken tones, and the utilisation of nature to suggest a personal language.