only sincerity

In brief, Manet was liberal and a humanitarian. He was a refined and cultivated man of the world, and it would be a mistake to think that his hunger for recognition (which was always bitterly disappointed) was a mere character trait. When presenting his personal exhibition in 1867, he wrote: “It is only sincerity that gives my work a character that could seem to be one of protest. In fact, the artist has tried only to express his impressions. He has no desire to overturn tradition or to create a new kind of painting. He has simply tried to be himself, and not someone else…”
[…]
From beginning to end, Manet’s life was really an impassioned affirmation of a single right—that of expressing a world of feelings that he had really experienced. The refined “dandy” who was full of irony and scepticism, and who loved the superficiality of life on the boulevards, became terribly serious when anyone mentioned his art. Manet’s attitude and the domineering way in which he expressed his ideas about painting needed to be justified by exceptional novelty and clarity of vision, and that he was justified is abundantly shown by the influence that his ideas have had on all art since his time. “Manet was the first,” Matisse wrote, “to work by reflexes and thus simplify the painter’s task…expressing only what affected his senses and feelings immediately.”

—Dario Durbe, Edouard Manet (Premier Book, Oldbourne Book Co. Ltd., 1963)