Question: Give that year that Van Gogh wrote to his brother about the Portrait of Dr. Gachet.
About the article "Portrait of Dr. Gachet", section "Background".

Candidate passages:
While Van Gogh was in Saint-Rémy, his brother, Theo and artist Camille Pissarro developed a plan for Van Gogh to go to Auvers-sur-Oise with a letter of introduction for Dr. Paul Gachet a homeopathic physician and art patron who lived in Auvers.
The plan also included him staying at a nearby inn while under the doctor's care.
Van Gogh had a room at the nearby Auberge Ravoux.
Van Gogh developed a close relationship with the doctor who he described as "something like another brother."
From the first meeting, though, Van Gogh sensed that Dr. Gachet may have been as ill as he.
In a letter from May 20, 1890, Van Gogh wrote, "I have seen Dr. Gachet, who made the impression on me of being rather eccentric, but his experience as a doctor must keep him balanced while fighting the nervous trouble from which he certainly seems to me to be suffering at least as seriously as I."
Van Gogh, introduced to etching by Gachet, made the etching "Portrait of Doctor Gachet" in 1890.
Gachet and Van Gogh discussed creating a series of southern France themes but that never happened.
This was the one and only etching, also known as "L'homme à la pipe" (Man with a pipe), that Van Gogh ever made.
Van Gogh's brother, Theo, who received an impression of the etching, called it "a true painter's etching.
No refinement in the execution, but a drawing on metal."
It is a different pose than that in Van Gogh's "Portrait of Dr. Gachet", owned by Musée d'Orsay.
The National Gallery of Canada finds that "The undulating flow of the line is typical of the expressive quality of Van Gogh's late style."
The impression owned by the National Gallery is from one of the 60 printings following Van Gogh's death by Dr. Gachet's son, Paul Gachet Jr. Gachet's collector's stamp appears on the bottom edge of the print. 
The Gachet Family.
"Portrait of Dr. Gachet" is one of the most revered paintings by Dutch artist Vincent van Gogh of Dr. Paul Gachet, who took care of him in his last months.
In 1990, it fetched a record price of $82.5 million ($75 million, plus a 10 percent buyer's commission).
Gachet was also an artist of the Impressionist era.
He was an amateur painter and engraver.
Vincent van Gogh went to the doctor for medical care.
Van Gogh saw himself in the doctor; like himself, he saw in Dr. Gachet “the heart-broken expression of our time.” Similar to many of van Gogh’s portraits, the painting is a study not of the physical features of the man, but of the inner qualities of the doctor’s personality.
The portrait of Dr. Gachet notes all the tiniest details of his appearance and depicts them in the way that van Gogh sees them.
The characteristics of the doctor’s image are all freely painted so that the viewer may see them the same way that van Gogh does. 
In May 1890, Van Gogh traveled from Saint-Rémy to Paris where he had a three-day stay with his brother, Theo, Theo's wife Johanna and their new baby Vincent.
Van Gogh found that unlike his past experiences in Paris, he was no longer used to the commotion of the city and was too agitated to paint.
His brother, Theo and artist Camille Pissarro developed a plan for Van Gogh to go to Auvers-sur-Oise with a letter of introduction for Dr. Paul Gachet, a homeopathic physician and art patron who lived in Auvers.
Van Gogh had a room at the inn Auberge Ravoux in Auvers and was under the care and supervision of Dr. Gachet with whom he grew to have a close relationship, "something like another brother."
Gachet and his daughter were both subjects for Van Gogh's paintings.
For a time, Van Gogh seemed to improve.
He began to paint at such a steady pace, there was barely space in his room for all the finished paintings.
From May until his death on July 29, Van Gogh made about 70 paintings, more than one a day, and many drawings.
Van Gogh painted buildings around the town of Auvers, such as The Church at Auvers, portraits, and the nearby fields.
"But for all his appearance of a renewed well-being," observes Wallace, "his life was very near its end."
Illness struck Theo's baby, Vincent.
Theo had both health and employment issues; he considered leaving his employer and starting his own business.
Gachet, said to have his own eccentricities and neurosis, caused Van Gogh sufficient concern to question, "Now when one blind man leads another blind man, don't they both end up in the ditch?
"After visiting Paris for a family conference, Van Gogh returned to Auvers more bleak.
In a letter he wrote, "And the prospect grows darker, I see no future at all."
In late June Van Gogh wrote of his interest to paint Marguerite Gachet, maybe in a country girl pose.
A few days later he wrote that he painted her in a pink dress playing a piano, and the previous day she had posed for this garden painting.
In "Marguerite Gachet in the Garden," Marguerite is dressed in white, "like a bride."
The garden of white roses and light lemon marigolds.
It was rumored in Auvers that Van Gogh considered Marguerite a friend and that she desired a relationship with him.
Dr. Gachet, though, had not given permission for the sittings and when he learned of the two sittings in two consecutive nights he was quite apprehensive about any relationship they might share.
Dr. Gachet asked Van Gogh to end his relationship with 21-year-old Marguerite.
Derek Fell, author of "Van Gogh's Women: Vincent's Love Affairs and Journey Into Madness" suggests that Van Gogh may have cared more deeply than imagined and been at least in part the reason for shooting himself.
In a letter to Theo Van Gogh expressed his sadness and frustration of not having a long-term partnership, "That desire marriage has left me, though the mental suffering of it remains.
"There were other concerns as well that affected Van Gogh at that time: the illness of Theo's baby, Theo's health and employment issues, potential loss of Theo's support and the destruction of his relationship with Dr. Gachet who was meant to manage Van Gogh's health and be a stabilizing influence.