Question: When did Seurat begin the painting?
About the article "A Sunday Afternoon on the Island of La Grande Jatte", section "Overview".

Candidate passages:
Paul Signac (1863–1935) was one of the most influential Neo-Impressionist painters of his time.
His name is synonymous with that of Georges Seurat (1859–91) as well as the practice of Color Theory.
One of his less well-known paintings, "The Lagoon of Saint Mark, Venice," (1905) is a prime example of his technique with pointillism and experiment with this color theory A beautiful depiction of an afternoon on a lagoon in Venice, this painting is a testament to Signac’s skill with seascape imagery.
The brilliant hues of blues and greens entice viewers and beckon all to book a ticket to go and see the dreamy view, firsthand.
When standing close to the painting, the only discernible features are the brush strokes that were so diligently and readily applied; this technique of painting was labeled, Pointilism, by Seurat.
Artists to use this technique after Seurat became known as Neo-Impressionists. 
 30 November - Folies Bergère stages its first revue.
Georges Seurat finishes painting Sunday Afternoon on the Island of La Grande Jatte some time this year.  
Georges Seurat spent over two years painting "A Sunday Afternoon", focusing meticulously on the landscape of the park.
He reworked the original as well as completed numerous preliminary drawings and oil sketches.
He sat in the park, creating numerous sketches of the various figures in order to perfect their form.
He concentrated on the issues of colour, light, and form.
The painting is approximately 2 by 3 meters (7 by 10 feet) in size.
Motivated by study in optical and color theory, Seurat contrasted miniature dots or small brushstrokes of colors that when unified optically in the human eye were perceived as a single shade or hue.
He believed that this form of painting, called divisionism at the time but now known as pointillism, would make the colors more brilliant and powerful than standard brush strokes.
The use of dots of almost uniform size came in the second year of his work on the painting, 1885–86.
To make the experience of the painting even more vivid, he surrounded it with a frame of painted dots, which in turn he enclosed with a pure white, wooden frame, which is how the painting is exhibited today at the Art Institute of Chicago.
In creating the picture, Seurat employed the then-new pigment zinc yellow (zinc chromate), most visibly for yellow highlights on the lawn in the painting, but also in mixtures with orange and blue pigments.
In the century and more since the painting's completion, the zinc yellow has darkened to brown — a colour degeneration that was already showing in the painting in Seurat's lifetime.
The island of la Grande Jatte is located at the very gates of Paris, lying in the Seine between Neuilly and Levallois-Perret, a short distance from where currently stands La Défense business district.
Although for many years it was an industrial site, it is today the site of a public garden and a housing development.
When Seurat began the painting in 1884, the island was a bucolic retreat far from the urban center.
The painting was first exhibited in 1886, dominating the second Salon of the Société des Artistes Indépendants, of which Seurat had been a founder in 1884.
In 1885 he met Georges Seurat and Paul Signac, both of whom relied on a more "scientific" theory of painting by using very small patches of pure colours to create the illusion of blended colours and shading when viewed from a distance.
Pissarro then spent the years from 1885 to 1888 practising this more time-consuming and laborious technique, referred to as pointillism.
The paintings that resulted were distinctly different from his Impressionist works, and were on display in the 1886 Impressionist Exhibition, but under a separate section, along with works by Seurat, Signac, and his son Lucien.
All four works were considered an "exception" to the eighth exhibition.
Joachim Pissarro notes that virtually every reviewer who commented on Pissarro's work noted "his extraordinary capacity to change his art, revise his position and take on new challenges."
One critic writes: "It is difficult to speak of Camille Pissarro ... What we have here is a fighter from way back, a master who continually grows and courageously adapts to new theories."
Pissarro explained the new art form as a "phase in the logical march of Impressionism", but he was alone among the other Impressionists with this attitude, however.
Joachim Pissarro states that Pissarro thereby became the "only artist who went from Impressionism to Neo-Impressionism".
In 1884, art dealer Theo van Gogh asked Pissarro if he would take in his older brother, Vincent, as a boarder in his home.
Lucien Pissarro wrote that his father was impressed by Van Gogh's work and had "foreseen the power of this artist", who was 23 years younger.
Although Van Gogh never boarded with him, Pissarro did explain to him the various ways of finding and expressing light and color, ideas which he later used in his paintings, notes Lucien. 
In 1882 Seurat rented a small studio in the rue Chabrol close to his family’s home.
"Bathers at Asnières" was painted in this studio, on a canvas identical in size to that part of "A Sunday Afternoon on the Island of La Grande Jatte" that excludes the painted border.
Following the rejection of the "Bathers" by the jury of the Salon of 1884, Seurat joined forces with some like-minded artists to become a founder members of the "Groupe des Artistes Indépendants".
This institution held its first exhibition—the "Salon de Artistes Indépendants"—between May 15th and July 1st, 1884 at a temporary building in the place du Carrousel, adjacent to the Louvre.
"Bathers at Asnières" is listed in the exhibition catalog as painting number 261, and it was displayed along with works from a total of 402 artists.
Despite the fact that Seurat was a founder member of the "Groupe", his painting was displayed in the unglamorous location of the exhibition beer hall, and appears to have had no great impact on spectators at the exhibition.
Later the same year, the Groups des Artistes Indépendants went on became the Société des Artistes Indépendants, and the "Bathers" was also hung at the first exhibition of the newly renamed "Société".
In 1886 Paul Durand-Ruel took the picture, along with some three hundred other canvases, to the National Academy of Design in New York, where he held his exhibition of the “Works in Oil and Pastel by the Impressionists of Paris.”The painting received mixed reviews from critics and commentators on both sides of the Atlantic.
The novelist and Biographer Paul Alexis commented equivocally, ‘This is a false Puvis de Chavannes.
What funny male and female bathers!
But it is painted with so much conviction that it appears almost touching and I don’t quite dare poke fun at it.’ In "L’Intransigeant", Edmond Bazire, writing under the pseudonym ‘Edmond Jacques’, wrote, ‘behind and under some prismatic eccentricities Seurat conceals the most distinguished qualities of draughtsmanship, and envelops his bathing men, his ripples, his horizons in warm tones.’ Both Jules Claretie and Roger Marx also described the painting as being a noteworthy ‘Impressionist’ painting.
"The Art Amateur"’s anonymous reviewer of the New York exhibition—who even explicitly likened "Bathers at Asnières" to Italian fresco painting—, also called the picture a modern ‘Impressionist’ work.
Paul Signac remarked that the "Bathers" was painted ‘… n great flat strokes, brushed one over the other, fed by a palette composed, like Delacroix’s, of pure and earthy colours.
By means of these ochres and browns the picture was deadened and appeared less brilliant than the works the impressionists painted with a palette limited to prismatic colours.
But the understanding of the laws of contrast, the methodical separation of elements--light, shade, local colour, and the interaction of colours--as well as their proper balance and proportion gave this canvas its perfect harmony.’Less flatteringly, an anonymous reviewer of Durand-Ruel’s Impressionist Exhibition in New York City wrote in the newspaper "The Sun" that, “The great master, from his own point of view, must surely be Seurat whose monstrous picture of "The Bathers" consumes so large a part of the Gallery D. This is a picture conceived in a coarse, vulgar, and commonplace mind, the work of a man seeking distinction by the vulgar qualification and expedient of size.
It is bad from every point of view, including his own.” This was by no means the only such uncomplimentary review in American and French newspapers.
But with the passage of decades, the "Bathers" slowly emerged into critical respectability.
The critic and friend of Seurat, Félix Fénéon waited many years before commenting, ‘Though I did not commit myself in writing, I then ["in 1884"] completely realised the importance of this painting.‘ For many years, "Bathers at Asnières" remained in the possession of Seurat’s family, and in 1900 the work was purchased by Felix Fénéon.
In 1924 it was purchased for the British national collections and hung in the Tate Gallery.
Seurat and the The Bathers.
John Leighton, Richard Thompson, et al, National Gallery Publications Limited.
London, 1997.
It was moved in 1961 to the National Gallery where it has remained since.X-ray imaging of the "Bathers" has revealed that some components of the composition were altered as Seurat’s work on the canvas progressed, while other components were probably not in the painting at all, as he first painted it.
The two reclining figures—one at the front of the image, the other with the straw hat toward the rear—are revealed by the X-ray image to have been among the later concerns for Seurat.
The reclining man at the front has had the position of his legs moved to a position more horizontal than that in which they were when first painted.
The reclining figure toward the rear is not visible in the X-ray image at all, showing he is a late addition.
His posture reflects the altered position of the man in the foreground, raising the suggestion that he was painted in as a compositional response to the alteration made to the man at the front.
The skiff and the ferry boat with the tricolor, and the pointillistically applied spots at various locations in the lower mid-section of the painting, are also absent in the X-ray image.
A contentious theory suggests that these elements were added by Seurat as a means of making a connection between the "Bathers" and "A Sunday Afternoon on the Island of La Grande Jatte".
In spite of their remoteness in the middle distance, the motifs and the seated figures on the boat are present in the later painting, and the ferry boat indeed traverses the river between the Courbevoie river-bank and the "île de la Grande Jatte" itself.
The late additions in "Bathers" bring for the first time a note of vitality to the serene picture in keeping with the more "sociable" climate of "A Sunday Afternoon on the Island of La Grande Jatte".