Question: Who was the inspiration behind Francis Bacon's series of paintings that began in 1957?
About the article "Vincent van Gogh", section "Influence".

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The film's opening credits include two paintings by Francis Bacon: "Double Por­trait of Lucian Freud and Frank Auerback" and "Study for a Portrait".
The hues used in the film were inspired by the paintings of Bacon.
During pre-production, Bertolucci frequently visited an exhibit of Bacon's paintings at the Grand Palais in Paris; he said that the light and colour in Bacon's paintings reminded him of Paris in the winter, when "the lights of the stores are on, and there is a very beautiful contrast between the leaden gray of the wintry sky and the warmth of the show windows...the light in the paintings was the major source of inspiration for the style we were looking for.
"Bacon's painting style often depicted human skin like raw meat and the painter's inspiration included meat hanging in a butcher shops window and human skin diseases.
Cinematographer Vittorio Storaro had previously worked with Bertolucci on "The Conformist" and often used an azure hue in the film.
Storaro later told a reporter that "after "The Conformist" I had a moment of crisis; I was asking myself: what can come after azure?...I did not have the slightest idea that an orange film could be born.
We needed another kind of emotion...
It was the case of "Last Tango".
For "Last Tango in Paris", Bertolucci and Storaro took inspiration from Bacon's paintings by using "rich oranges, light and cool grays, icy whites, and occasional reds combine with Bertolucci's own tasteful choices of soft browns, blond browns, and delicate whites with bluish and pink shadings.
"Bertolucci took Marlon Brando to the Bacon exhibit and told Brando that he "wanted him to compare himself with Bacon's human figures because I felt that, like them, Marlon's face and body were characterized by a strange and infernal plasticity.
I wanted Paul to be like the figures that obsessively return in Bacon: faces eaten by something coming from the inside."
Head VI is a 1949 oil on canvas painting by the Irish-born British figurative artist Francis Bacon, the final of the six panels of his 1949 "head" series.
It shows a bust view of a single figure, probably a pope, who is shown behind horizontal curtain-like drapes.
The overall effect is of a figure trapped and suffocated by his surroundings and circumstance, screaming in vain into an airless glass-sealed void.
The work is noted for its physical, expressive brush strokes and for being Bacon's first work to refer to Diego Velázquez's "Portrait of Innocent X", a painting that was to haunt the artist; "Head VI" is the first of Bacon's "screaming popes", which total more than 45 individual works.
"Head VI" contains many painterly motifs that were to reapper in Bacon's work.
The hanging object that may be a light switch or curtain tassel, can be found even in his late paintings.
It is the second painting– after his 1949 "Study for Portrait" – in which the sitter is enlcosed within a geometric cage; many other examples were to follow; and appear as late as his masterpiece, the "Study for a Self-Portrait—Triptych, 1985–86".
By 1949 Bacon was a highly controversial but mostly respected artist, the "enfant terrible" of British art.
This work drew mixed criticism.
John Russell, who became one of the artist's firmest supporters, dismissed it as a cross between an "alligator shorn of its jaws and a bespectacled accountant".
In 1989 Lawrence Gowing wrote that the "shock of the picture, when it was seen with a whole series of heads in Bacon's exhibition a the Hanover Gallery in London at Christmas 1949, was indescribable.
It was everything unpardonable.
The paradoxical appearance at once of pastiche and iconoclasm was indeed one of Bacon's most original strokes.
The picture remains one of his masterpieces and one of the least conventional, least foreseeable pictures of the twentieth century."
" "Head VI" was first exhibited in November 1949, in a showing organised by one of the artist's early champions, Erica Brausen.
David Sylvester described it in 2000 as the most seminal piece from Bacon's unusually productive 1949–50 period, and one of Bacon's finest "Popes". 
As an artist, Francis Bacon was a late starter.
He painted sporadically and without commitment during the late 1920s and early 1930s, when he worked as an interior decorator and designer of furniture and rugs.
He later admitted that his career was delayed because he had spent so long looking for a subject that would sustain his interest.
He began to paint images based on the Crucifixion in 1933, when his then-patron Eric Hall commissioned a series of three paintings based on the subject.
These abstract figurations contain formal elements typical of their time, including diaphanous forms, flat backgrounds, and surrealist props such as flowers and umbrellas.
The art critic Wieland Schmied noted that while the early works are "aesthetically pleasing", they lack "a sense of urgency or inner necessity; they are beautiful, but lifeless."
The sentiment is echoed by Hugh Davies, who wrote that Bacon's 1933 paintings "suggest an artist concentrating more on formal than on expressive concerns."
Bacon admitted that his early works were not successful; they were merely decorative and lacking in substance.
He was often harshly self-critical during this period, and would abandon or destroy canvasses before they were completed.
He abandoned the Crucifixion theme, then largely withdrew from painting in frustration, instead immersing himself in love affairs, drinking and gambling.
When he returned to the topic of the Crucifixion eleven years later, he retained some of the stylistic elements he had developed earlier, such as the elongated and dislocated organic forms that he now based on "The Oresteia".
He continued to incorporate the spatial device he was to use many times throughout his career—three lines radiating from this central figure, which was first seen in "Crucifixion, 1933".
"Three Studies" was painted over the course of two weeks in 1944, when, Bacon recalled, "I was in a bad mood of drinking, and I did it under tremendous hangovers and drink; I sometimes hardly knew what I was doing.
I think perhaps the drink helped me to be a bit freer."
The painting was executed in a ground-floor flat at 7 Cromwell Place, South Kensington in London.
A large back room in the building had been converted into a billiard room by its previous occupant, artist John Everett Millais.
It was Bacon's studio by day; at night, abetted by Eric Hall and Bacon's childhood nanny Jessie Lightfoot, it functioned as an illicit casino.
Although he had been painting for almost twenty years, Bacon steadfastly insisted that "Three Studies" was the "fons et origo" of his career.
He destroyed many of his earlier canvasses, and tried to suppress those that had left his studio.
Bacon was emphatic that no pre-1944 images be admitted into his canon, and most of the early art critics agreed with this position.
The early publications of John Russell and David Sylvester open with the 1944 triptych, and Bacon insisted to his death that no retrospective should feature paintings pre-dating 1944. 
All three panels, in Bacon's typical abstract, distorted, isolated style, show Freud sitting on a cane-bottomed wooden chair within a cage, on a curved mottled-brown surface with a solid orange background.
Behind each figure is a headboard of a bed, originating in a set of photographs of Freud by John Deakin which Bacon used as a reference.
Michael Peppiatt writes "Trapped here in a series of Baconian cages, a contorted Freud hovers from panel to panel like a coiled spring about to shoot out of the flat, airless picture plane."
The central panel portrays the figure face on, in a pose similar to that Bacon used for George Dyer, his lover.
Brett Gorvy of Christie's considers the work to represent "a marriage of the incredibly important people in Bacon's life."
The three canvases of the triptych are the same size and are each individually framed.
The colouring is brighter than typical of Bacon's works.
Francis Outred of Christie's describes the 1969 triptych as "a true masterpiece" and "an undeniable icon of 20th Century art" which "marks Bacon and Freud's relationship, paying tribute to the creative and emotional kinship between the two artists."
Art historian Ben Street describes the work as "not an A-grade Bacon."
It was among Bacon's favourites of his works. 
Robert Stephens (1665–1732), who was appointed historiographer royal in 1727, was a public servant and historian.
He was the first to publish much of Francis Bacon's private correspondence.