One of the great mysteries artists leave behind when they die is the source of their inspiration. Sometimes it's obvious: in the case of French Impressionist Claude Monet, it was his surroundings - the water garden at Giverny or his house at Argenteuil. Pablo Picasso's cubism was fired by war and politics. But often the most famous artists required further inspiration than simply the world around them to arouse their creativity. They needed a muse.
This week it was revealed that the artist and sculptor Alberto Giacometti - whose L'Homme Que Marche II sold for a record-breaking £65m (Dh380) earlier this year - had such a woman during the last years of his life in the mid-1960s. She was rather famous, too - the drawings recently uncovered in the Giacometti archive weren't of some hitherto unknown woman, but Christine Keeler. Photographs of the model at the heart of the Profumo affair, which threatened to bring down the British establishment in 1963, had appeared in a French newspaper, and Giacometti had begun sketching her in the margins.
Giacometti was, perhaps, a little ahead of his time. He and Keeler never actually met - in a sense, she was his virtual inspiration. But the idea is the same; a muse should never be a paid model or a subject. There was much excitement when Lucian Freud's famous Benefits Supervisor Sleeping sold for £17.2m in 2008 - but the model Sue Tilley wasn't really his muse in the truest sense of the word. She posed for him for £20 a day for nine months. That's a job, not a meeting of creative minds.
For the real muse of 20th-century art, look no further than Elena Ivanova Diakonova - more famously known as Gala. There was something in this Russian emigre that captured the imaginations (and hearts) of artists - particularly the surrealists. Her first marriage to Paul Eluard provoked many of his finest love poems - and when the relationship ended (Gala running off with Salvador Dali) he admitted that he had, in some ways, "invented" her in his mind. It was a similar story for Dali, with whom she lived until her death in 1982. Gala featured in many of his most famous works, and it's no surprise that after she died Dali was not only creatively spent, but emotionally, too.
Still, the role of a muse is to help channel and tease out the artist's creative energy rather than be an unquestioning girlfriend. Look back through the history of art, and sometimes this made this key relationship complicated.
Gustav Klimt's relationship with Emilie Flöge was puzzling to say the least. They lived together for most of her life, but he had his 14 children with other women. Klimt's representations of his companion were as a bejewelled icon, but never as a siren or femme fatale. She looked elegant, venerated and very much the muse - as is obvious in one of Klimt's most famous works, The Kiss.
The idea of the muse is not exclusive to art, of course. When The Beatles were making a name for themselves in the clubs of 1960s Hamburg, it was a certain Astrid Kirchherr - the girlfriend of "fifth Beatle" Stuart Sutcliffe - who encouraged them to comb their hair forward into a moptop. Kirchherr took the stylised black-and-white photographs around the German port city that immediately made them a cool band rather than just a gang of Liverpool mates. Was she a muse, or just someone well practised in PR? The Beatles were certainly taken in - Cynthia Powell, John Lennon's girlfriend back home in England, was insanely jealous of letters full of "Astrid said this, Astrid did that".
Perhaps, though, it shouldn't be surprising that artists need a special someone to bounce ideas off. The trappings of their life - the fame, the glory, the critical adulation - are all very well. But the actual process of dreaming up and then creating art is almost always a rather dull and lonely existence, full of self-doubt. Maybe, in absent-mindedly doodling images of Christine Keeler on his newspaper, Giacometti was actually willing himself a companion.
