Explain how postimpressionism reflects the art-for-art's-sake spirit

What will be an ideal response?

Postimpressionism built on the abstract experimentation of impressionism, giving increased emphasis to color and compositional form. Postimpressionist artists embraced an "art-for-art's sake" aestheticism that prized pictorial invention over pictorial illusion. Strongly individualistic, they were uninterested in satisfying the demands of public and private patrons; most of them made only sporadic efforts to sell what they produced.
The aesthetics of the postimpressionist style can be seen in the works of Van Gogh. Van Gogh painted landscapes, still lifes, and portraits in a style that featured flat, bright colors, a throbbing, sinuous line, short, choppy brushstrokes, and bold compositions that betray his admiration for Japanese woodblock prints. He shared with the Romantics an attitude toward nature that was both inspired and ecstatic. His emotional response to an object, rather than its physical appearance, influenced his choice of colors, which he likened to orchestrated sound. As an artist, van Gogh pledged his undying faith in the power of artistic creativity, working in practical isolation, Van Gogh confessed that he saw himself as a simple Buddhist monk.