Question: Who is Van Gogh's brother?
About the article "The Starry Night", section "Subject matter".

Candidate passages:
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. 
While in Saint-Remy interest began to build in van Gogh's work:   Theo, Van Gogh's brother, wrote in July 1889, that Camille and Lucien Pissarro, Père Tanguy, Erik Theodor Werenskiold and Octave Maus, secretary of the Les XX group in Brussels, had seen the paintings that he'd made in southern France.
On Van Gogh's behalf, Theo accepted an offer from Maus to exhibit Van Gogh's work at the Les XX group's upcoming exhibition.
Van Gogh's "Starry Night over the Rhone" and "The Irises" were exhibited at the Société des Artistes Indépendants on the third of September.
In January, 1890 six of Van Gogh's works were exhibited at the seventh exhibition of Les XX in Brussels along with, among others, Paul Cézanne, Camille Pissarro, Pierre-Auguste Renoir, Paul Signac and Henri de Toulouse-Lautrec.
Van Gogh's painting "The Red Vineyard" was sold to artist Anna Boch at the exhibition for 400 francs.
In the same month an article is published "Les Isole: Vincent van Gogh" in the "Mercure de France".
Ten of Van Gogh's works were presented at the March, 1890 Société des Artistes Indépendants.
Paul Gauguin, Claude Monet and Pissarro were quite impressed with his works.
Over this time, though, Van Gogh's health ebbed and flowed between periods of attacks, recovery and resumption of painting.
In April, 1890, near the end of van Gogh's stay at Saint-Paul's hospital, Theo wrote to his sister and mother, "I am so pleased that Vincent's work is being more appreciated.
If he were fit I believe that there would be nothing for me to desire, but it appears that this is not to be.
"The sale of "Red Vineyard" was the only sale of van Gogh's paintings made during his lifetime. 
Art dealer Pierre Firmin-Martin, a friend of Van Gogh's brother Theo, displayed some of Van Gogh's paintings.
"Mother by a Cradle, Portrait of Leonie Rose Davy-Charbuy" was made of Martin's niece who lived with her uncle.
Reflective of the family's interest in art, paintings hang in the background.
In the year the painting was made Theo commented that Van Gogh done a good job painting portraits but had never asked for payment. 
"Vase with Zinnias and Geraniums" (F241) reflects the influence of Adolphe Monticelli (1824–1886) in its vivid color and impasto paint.
Van Gogh admired, and later collected, Monticelli's work.
Van Gogh had been introduced by his brother Theo to Monticelli's still life work with flowers in Paris.
He admired Monticelli's use of color as an expansion of Delacroix's theories of color and contrast.
Secondly he admired the effect Monticelli created by heavy application of paint called "impasto".
It was partially Monticelli, from Marseilles, who inspired Van Gogh's southerly move to Provence in 1888.
He felt such kinship for the man, and desire to emulate his style, that he wrote in a letter to his sister Wil that he felt as if he were "Monticelli's son or his brother."
The first owner in the provenance of this painting is "C.M.
van Gogh Gallery, Amsterdam, The Netherlands", which was owned by Van Gogh's uncle and an art dealer, Cornelius Marinus van Gogh (1824–1908).
"Bowl with Zinnias and Other Flowers" (F251), painted within days of "Vase with Zinnias and Geraniums" (F241), is evidence of Van Gogh's transition to a lighter color palette.
Picking up elements of Impressionism Van Gogh painted with a more vigorous brushstroke, with thick application of paint, called "impasto" which created a three-dimensional relief.< 
Vincent van Gogh's display at Les XX, 1890, in Brussels is an important testament to the recognition he received amongst avant-garde peers during his own lifetime.
Participation in the annual exhibition of Les XX was for members and by invitation only.
Van Gogh's choice proves that he was going for more than a simple selection of paintings he considered superior, but that he was willing to provide a well reasoned summary of his years of work in Provence.
Evidently this notion remained neglected, and even more: it was washed away by the scandal his works provoked.
Then the same works were again shown at the annual exhibition of the Artistes Indépendants in Paris which offered space for an expansion of the display: this was done by Theo van Gogh, the brother of Vincent, who was suffering from long lasting mental problems.