TORONTO -- A letter written jointly by Vincent Van Gogh and fellow post-Impressionist painter Paul Gauguin -- detailing brothel visits, their painting progress and frank assessments of each other -- has sold at auction for around $321,000.

The Vincent Van Gogh Foundation acquired the letter at a Paris auction house on Tuesday. According to a press release, they consider it to be the “most significant document written by Van Gogh that was still in private hands.”

It is the only known letter that Van Gogh has penned with another writer.

“Gauguin interests me greatly as a man -- greatly,” he reveals in the letter.

The letter was written on November 1 or 2 of 1888, shortly after Gauguin had arrived to stay at the Yellow House in Arles, in the south of France, where Van Gogh lived and produced some of his most vibrant art. Van Gogh dreamed of creating an artists’ paradise in Arles, and Gaugin’s arrival was a step towards that goal.

Their time living together would turn out to be brief, but intense, ending with Gauguin leaving in December around the same time that Van Gogh infamously cut off his own ear.

Although the letter is addressed to another artist, Emile Bernard, the text contains almost a dialogue between Van Gogh and Gauguin themselves, reflecting on their views on art and each other.

Van Gogh described Gauguin as “an unspoiled creature with the instincts of a wild beast.”

“With Gauguin,” he wrote, “blood and sex have the edge over ambition.”

After finishing his portion of the letter, he leaves space at the bottom for Gauguin to add his own short message to Bernard, and Gauguin takes the opportunity to share his opinion of the other artist.

“Don’t listen to Vincent; as you know, he’s prone to admire and ditto to be indulgent,” Gauguin wrote.

The letter also contains numerous references to paintings the two were working on -- and where they went for inspiration.

“Now something that will interest you -- we’ve made some excursions in the brothels, and it’s likely that we’ll eventually go there often to work,” Van Gogh wrote. A painting Van Gogh created in October of 1888 called “The Brothel” seems to depict one of the brothels that he visited.

After Van Gogh cut off his ear in December of that year, he reportedly gave it to a woman who worked as a maid at a brothel.

“At the moment Gauguin has a canvas in progress of the same night café that I also painted, but with figures seen in the brothels,” the letter continues.

The painting he refers to is likely “Night Cafe at Arles (Madame Ginoux),” where Gauguin painted Madam Ginoux, a woman Van Gogh had also painted earlier, sitting inside of a cafe that the two frequented. Three figures in the background of the painting are thought to be from the brothel that Van Gogh mentions in the letter.

Van Gogh’s earlier painting of this same cafe is called “The Night Cafe,” and also depicts the inside of the Cafe de la Gare, though it focuses on the colours of the room and does not have one central human figure.

The two artists both wrote of their feeling that they were at the forefront of a great art movement, and that the future of art was just around the corner.

Van Gogh wrote that he believed “in the possibility of a great renaissance of art.

“It seems to me that we ourselves are serving only as intermediaries. And that it will only be a subsequent generation that will succeed in living in peace.”

Van Gogh was plagued with depression and other mental health issues throughout his life. He died in 1890 from a gunshot wound. It is widely believed that he died of suicide, although some have speculated that he may have been shot by someone else. 

Although Van Gogh and Gauguin never saw each other again in person after that fateful day in December when Gauguin left, the two continued to correspond through letters until Van Gogh’s death.

The letter will be displayed by the Van Gogh Museum in Amsterdam in an exhibit of the Dutch painter’s letters called “Your loving Vincent,” in October.