What and how is/are the principle(s) of art, most/not characteristic of Impressionism in A Bar at the Folies-Bergère?

When Manet painted "A Bar at the Folies-Bergère" in 1882, the Impressionist movement had been underway in Paris for almost 10 years. Therefore, we should see this painting as a response to impressionism, in the sense that it adopts the impressionist painting style but offers a counter-perspective to the way impressionist paintings presented modern life. 

The impressionist movement followed the realist movement, which was about presenting poor and ordinary people in daily life. When Manet began painting in the 1860s, realism was still popular, so he internalized some of their traditions. We can see this in "A Bar at the Folies-Bergère." The woman behind the counter is working class and seems tired and depressed (like many people who work in customer service), so this painting accurately reflects the realities of working class modern life. This is very much in keeping with the realist tradition established by artists such as Gustave Courbet and Honoré Daumier, who painted scenes from the daily lives of poor people. 

The impressionists also painted ordinary scenes from modern life, but tended to focus on the lives of the middle and upper classes. Common themes in Impressionist paintings are leisure, contemplation, and the excitement of city life. Well known Impressionist paintings that feature people are Claud Monet's "On the Bank of the Seine, Bennecourt" (1868), Pierre-Auguste Renoir's "Moulin de la Galette" (1876), and Mary Cassatt's "Woman in a Loge" (1879). The first features a woman sitting under a tree on the banks of the Seine, gazing calmly out onto the water, where we see two people on a rowboat, and quaint houses in the background. The second painting, "Moulin de la Galette," takes place in a dancehall in Paris on a Sunday afternoon. A mood of carefree innocence animates the scene, as everyone is either dancing or engaged in conversation. In reality, the Moulin de la Galette was frequented by working class people, but Renoir chose to depict a more upper class clientele to make the image more pleasant to look at. In "Woman in a Loge," an elegantly dressed woman is at the opera, in front of a mirror. Reflected behind her we see the other people in the crowd, all equally well dressed and enjoying the moment. 

"A Bar at the Folies-Bergère" contrasts sharply with these three hallmarks of impressionism. The woman behind the counter could be imagined as the person serving the partygoers in either the Renoir or Cassat painting, and she is not having the fun that that the other subjects are having. While Renoir and Cassat make modern city life seem full of exciting opportunities, Manet counters with a scene of the dreary, alienating work that city life offers. While Monet shows us a tranquil scene of quiet contemplation, Manet shows us a busy scene where the subject has no time or space to contemplate. 

At the same time, Manet follows the lead of the Impressionists by, like them, using a light color palette and loose brushwork. Like in "Moulin de la Galette" or "Woman in a Loge," the faces of the people at the bar in "Folies-Bergères" are blurred, which creates a sense that they are in motion. Manet's brushwork has the same effect as Renoir and Cassat's - the crowd is alive, there is excitement in the air. The difference is that he takes a more cynical view of that excitement - it is at the expense of working class people. Like Monet, Manet used light to set a mood, but while Monet's bright sunlight reflected on the water and on the back of the sitting subject sets a tranquil mood, Manet's dim light of the chandelier sets a bleaker mood. 

In sum, Manet's use of light, his color palette, the setting of his scene, and especially his loose brushwork, are very characteristic of Impressionism. However, his subject matter and pessimistic viewpoint are not at all characteristic of impressionism.