(a) "The [1866] painting itself, 'The Origin of the World' * * * is now at the Musée d'Orsay in Paris, where it has been on public display since 1995.
(b) "[French historian] Claude Schopp * * * Mr Schopp's moment of breakthrough came innocently enough. He had been working on annotating the letters between Dumas and the writer George Sand, and had long been perplexed by a passage, in the old typewritten copies, where Dumas inveighs against the 'insolent' and 'cowardly' Courbet, who had committed an artistic heresy, in the view of Dumas:
" 'One doesn't paint with one’s most delicate and sonorous brush the interview of Ms [Constance] Queniault of the Opera, for the Turk who took refuge inside it from time to time — all of it life-size, and life-size also two women passing for men.'
"The reference to the painting of the 'two women passing' was easily enough identified: 'Sleep,' Courbet’s scandalous painting of two reclining women, naked and intertwined. The 'Turk' who commissioned it was also not difficult to pin down: the wealthy Ottoman diplomat Khalil Bey, who had lived a notoriously lavish life in the Paris of the 1860s, full of sumptuous soirees, gambling and mistresses, which piled up the debts that eventually ruined him.
(c) "The word Dumas had actually written was 'interior,' not interview. He underlined it, to emphasize that he was playing with words.
" 'I dared to utter an inner "Eureka," ' Mr Schopp writes in a new book about the affair, 'The Origin of the World: Life of the Model,' which will be published this week. Khalil Bey had also commissioned 'The Origin of the World,' and this 'Ms Queniault' [the last name should be Quéniaux] — the name had been slightly misspelled — was evidently one of his mistresses.
Note:
(a) Musée d'Orsay https://en.wikipedia.org/wiki/Musée_d%27Orsay
(1986- ; in Paris; The museum building was originally a railway station, Gare d'Orsay)
(i) The museum's English-language Web page says, "The Musée d'Orsay is a national museum responsible to the Ministry of Culture."
(ii) Orsay https://en.wikipedia.org/wiki/Orsay
(a commune southwest of, and outside, Paris; "From the sixteenth century, the town and surrounding area were owned by the Boucher family, and it was in honour of this family that Louis XIV gave the quai d'Orsay its name. This is the reason that the Musée d'Orsay is not in Orsay")
(iii) Quai d'Orsay (disambiguation) https://en.wikipedia.org/wiki/Quai_d%27Orsay_(disambiguation)
("is the name of a street along the Seine [as well as that of a neighborhood by that street] in Paris, used as a dock in the Middle Ages")