The late nineteenth century is often cited as a critical point in the development of a "modern" art. Impressionists and Post-Impressionists turned to the contemporary world as primary subject matter, and depicted elements of that world using an innovative style. Carefully examine the following paintings: Monet, Rouen Cathedral: The Portal (In Sun), 1894 Manet, Bar at the Folies-Bergere, 1881-82 Seurat, A Sunday Afternoon on the Island of La Grande Jatte, c. 1884-86 In 3 well-developed paragraphs, address the following questions:

How is the subject of each painting representative of Impressionism or Post-Impressionism?

Describe the specific ways that each painting shows tension between its inherent two-dimensionality and any illusion of three-dimensionality created by the artist.

Monet, Rouen Cathedral: The Portal (In Sun) 1894

The painting is a representative of an Impressionist painting. Because Monet's work captures the facade of the Cathedral at different times of the day and year, thus reflecting the changes in its appearance under different conditions of light and colour. The painting has a groundbreaking 'Gothic style'. It is a style that usually characterized as a style of masonry building that makes heavy use of cavernous spaces with walls broken up by overlaid tracery, Typical architectural features 

Monet painted the facade with highly textured brushstrokes that convey the aspect of sculpted stone and make the atmosphere and light palpable. Monet later finished the works in his studio at Giverny, carefully adjusting the pictures both independently and in relation to each other. 

He observed the haystacks in a field in Giverny in all weathers, then, on the banks of the Epte, painted the poplars at different times of the day, he took for his subject a cathedral under the same conditions. His painting technique was still changing; his paint became a sort of stippled cement as if to imitate the grain of the old stones and was painted in full sunshine. Others were done in a grey dawn, or at twilight, in the fires of sunset, or again all veiled in mist. The painting was classified this series of cathedrals in four groups, the greys, the whites, the blues, and the rainbow hued. 

Manet, Bar at the Folies-Bergère, 1881-1882

It is a representative of Impressionism movement. The painting represents the bustling interior of one of the most prominent music halls and cabarets of Paris, the Folies-Bergère and its atmosphere was described as "unmixed joy". In contrast, the barmaid in Manet's representation is detached and marooned behind the bar.

Bar at the Folies-Bergère features a modern setting in The Folies-Bergere - the most famous and modern of Paris's cafe-concert halls, which was noted among other things for its new-fangled electric lights and  maintains the artist's contradictory outlook. Its brushwork is Impressionistic and its framing has been influenced by the new art of photography. On the other hand, its meaning is totally obscure, even baffling, dealing as it does with a problem that occupied Manet throughout his working life: the relationship, in figurative painting, between reality and illusion.

Looking and observing the painting, a huge amount of analysis is devoted to the artwork in an attempt to decipher its meaning, and reconcile the apparent dislocation between the actual reality of the barmaid and her counter, and the surreal reflections in the mirror. Instead of standing parallel to the bar and looking straight ahead, she is facing slightly to the right of the picture as we see it, facing the new viewpoint.

Seurat, A Sunday Afternoon On The Island Of La Grande Jatte, c. 1884-1886

A Sunday Afternoon On The Island Of La Grande Jatte is a representation of Post-Impressionism movement artwork. The painting is Seurat's final study for his monumental painting of Parisians at leisure on an island in the Seine (Art Institute of Chicago). The technique he settled on involved the use of small touches of pure colour, which are not mixed but placed side by side on the canvas. When viewed from a certain distance, these touches of colour blend together. In effect, the colour pigments are mixed together by the eye, rather than by the artist.

The painting was painstakingly planned from start to finish in the manner of a Greek frieze, and its (often) symbolic content positively invites careful scrutiny. It depicts fashionable Parisians enjoying a Sunday afternoon at a popular beauty spot located on the River Seine between Neuilly and Levallois-Perret. While his earlier Bathers at Asnieres depicted the working class left-bank of the river, this work shows the bourgeois right-bank at La Grande Jatte. It is, for instance, in contrast to the unremitting heat of Asnieres, La Grande Jatte has plenty of cool shade in which to escape the sun.

Seurat used contrasting pigments that were woven together with small, patchy brushstrokes, whereas in the mural-sized park scene. Also, Seurat used tighter, dot-like dabs of paint, a technique which came to be known as Pointillism and more preferred the term Divisionism which is the principle of separating color into small touches placed side-by-side and meant to blend in the eye of the viewer.

Step-by-step explanation

To come up with the above answers, I opened and read the attached document to know the full details of the given questions. From there, I researched and read meaningful information about the given title of paintings. I gave all the vital details that will best answer and explain each of the painting.