The most comprehensive primary source on Van Gogh is the correspondence between him and his younger brother, Theo. Their lifelong friendship, and most of what is known of Vincent's thoughts and theories of art, are recorded in the hundreds of letters they exchanged from 1872 until 1890. Theo van Gogh was an art dealer and provided his brother with financial and emotional support, and access to influential people on the contemporary art scene.
Van Gogh drew, and painted with watercolours while at school, but only a few examples survive and the authorship of some has been challenged. When he took up art as an adult, he began at an elementary level. In early 1882, his uncle, Cornelis Marinus, owner of a well-known gallery of contemporary art in Amsterdam, asked for drawings of The Hague. Van Gogh's work did not live up to expectations. Marinus offered a second commission, specifying the subject matter in detail, but was again disappointed with the result. Van Gogh persevered; he experimented with lighting in his studio using variable shutters, and with different drawing materials. For more than a year he worked on single figures – highly elaborate studies in black and white,[note 11] which at the time gained him only criticism. Later, they were recognised as early masterpieces.
Penniless and feeling that his faith was destroyed, he sank into despair and withdrew from everyone. “They think I’m a madman,” he told an acquaintance, “because I wanted to be a true Christian. They turned me out like a dog, saying that I was causing a scandal.” It was then that van Gogh began to draw seriously, thereby discovering in 1880 his true vocation as an artist. Van Gogh decided that his mission from then on would be to bring consolation to humanity through art. “I want to give the wretched a brotherly message,” he explained to his brother Theo. “When I sign [my paintings] ‘Vincent,’ it is as one of them.” This realization of his creative powers restored his self-confidence.
By March 1882, Mauve appears to have gone cold towards Van Gogh, and stopped replying to his letters. He had learned of Van Gogh's new domestic arrangement with an alcoholic prostitute, Clasina Maria "Sien" Hoornik (1850–1904), and her young daughter. Van Gogh had met Sien towards the end of January 1882, when she had a five-year-old daughter and was pregnant. She had previously borne two children who died, but Van Gogh was unaware of this; on 2 July, she gave birth to a baby boy, Willem. When Van Gogh's father discovered the details of their relationship, he put pressure on his son to abandon Sien and her two children. Vincent at first defied him, and considered moving the family out of the city, but in late 1883, he left Sien and the children.
The police found van Gogh in his room the next morning, and admitted him to the Hôtel-Dieu hospital. Theo arrived on Christmas Day to see van Gogh, who was weak from blood loss and having violent seizures. The doctors assured Theo that his brother would live and would be taken good care of, and on January 7, 1889, van Gogh was released from the hospital.
By this time van Gogh was ready for such lessons, and the changes that his painting underwent in Paris between the spring of 1886 and February 1888 led to the creation of his personal idiom and style of brushwork. His palette at last became colourful, his vision less traditional, and his tonalities lighter, as may be seen in his first paintings of Montmartre. By the summer of 1887 he was painting in pure colours and using broken brushwork that is at times pointillistic. Finally, by the beginning of 1888, van Gogh’s Post-Impressionist style had crystallized, resulting in such masterpieces as Portrait of Père Tanguy and Self-Portrait in Front of the Easel, as well as in some landscapes of the Parisian suburbs.