Question: Why is it fitting "Marchesa Casati" was painted by Augustus John?

Context paragraphs:
Lilian Shelley: Lilian Shelley (born Lilian Milsom) (1892 - after 1933) was a popular music hall entertainer and later artists' model in London in the early 1900s known as "The Bug" or "The Pocket Edition".  She posed for Jacob Epstein and Augustus John.  John's portrait of Shelley was described as one of the "star turns" in an exhibition "Pictures of Women" at the Wildenstein Galleries, London, in 1940.  He called her "Bill".

Euphemia Lamb: Euphemia Lamb (c.1889–1957), born Nina Forrest (some sources, as well as publicly available records, alongside giving her first name as 'Anne', indicate her middle name was actually Euphemia, casting doubt on the tentative claim that Henry Lamb perceived in her a likeness to Saint Euphemia) was an artists' model and the wife of Henry Lamb.  She modelled for Augustus John and Jacob Epstein and came to exemplify the sexual freedom of the bohemian lifestyle of the early twentieth century.  Henry Lamb renamed her Euphemia, by which name she was generally known.  John Maynard Keynes commented that Euphemia had more of a sex life "than the rest of us put together".  She was one of the lovers of the occultist Aleister Crowley.

A Matter of Time (film): A Matter of Time is a 1976 American-Italian musical fantasy film starring Liza Minnelli and Ingrid Bergman, directed by Vincente Minnelli.  The screenplay by John Gay is based on the novel "The Film of Memory" by Maurice Druon.  The fictional story is based loosely on the real life exploits of the infamous Italian eccentric, the Marchesa Casati, whom Druon knew during her declining years in London while he was stationed there during World War II.  The film marked the first screen appearance for Isabella Rossellini, the last for Charles Boyer, and it proved to be Vincente Minnelli's final project.

Gwen John: Gwendolen Mary John (22 June 1876 – 18 September 1939) was a Welsh artist who worked in France for most of her career.  Her paintings, mainly portraits of anonymous female sitters, are rendered in a range of closely related tones.  Although she was overshadowed during her lifetime by her brother Augustus John, her reputation has grown steadily since her death.

Scot D. Ryersson: Scot D. Ryersson (September 10, 1960 in Suffern, New York) is an illustrator, graphic artist and writer.  In addition to many critiques and essays on film and literature, he is the co-author of the biography "Infinite Variety: The Life and Legend of the Marchesa Casati", as well as "The Marchesa Casati: Portraits of a Muse".

John Hope-Johnstone (photographer): Charles John Hope-Johnstone (1883-1970) was a British photographer and a member or associate of the Bloomsbury Group He served as editor of the "Burlington Magazine" from 1919-1920 and tutored the children of Augustus John.  He had walked to Bosnia with Gerald Brenan before World War I, and introduced the latter to the Bloomsbury Group in 1919.  For many years, until his death, he lived in a tiny cottage attached to Gerald Brenan's house in Aldbourne, Wiltshire.

Marchesa Casati (painting): The Marchesa Casati (] ) is a portrait of Luisa Casati by Augustus John, painted in oil on canvas in 1919.  It is currently housed in the collection of the Art Gallery of Ontario (AGO) in Toronto.

Crab Tree Club: The Crab Tree Club was a nightclub in Greek Street, Soho, London, that was established by the painter Augustus John in April 1914 with the financial support of Thomas Scott-Ellis (Lord Howard de Walden).  John wrote to his friend John Quinn, "We are starting a new club in town called the 'Crab-tree' for artists, poets and musicians... It ought to be amusing and useful at times".  The club was a popular meeting place for London bohemians immediately before the First World War who would descend en-masse on the Crab Tree after the Café Royal closed for the night.

Dorelia McNeill: Dorothy (Dorelia) McNeill (19 December 1881 – 23 July 1969) was best known as a model for the Welsh artists Gwen John and Augustus John, was the common-law wife of the latter, and has been credited for inspiring "his first unequivocally personal work".  In her time she was regarded by some as an exemplar of bohemian fashion.

Luisa Casati: Luisa, Marchesa Casati Stampa di Soncino (23 January 1881 – 1 June 1957), also known as Luisa Casati, was an Italian heiress, muse, and patroness of the arts in early 20th-century Europe known for her eccentricities.  As the concept of quaintrelle was re-developed, Marchesa Casati fitted the utmost example by saying: "I want to be a living work of art".

Supporting paragraphs: Marchesa Casati (painting) Luisa Casati
Answer: I want to be a living work of art