Lee Siegel gave a sweeping history of muse-dom in Saturday’s Wall Street Journal:

The original muse could not have been further from an exemplar of style. Her function was not to inspire imitation, but to create new insights and new artistic forms. She was effectively invisible, a gust of divine wind that blew through the human vessel lucky enough to be graced by her attention.

In ancient times, the muse was a divinity, daughter of Zeus and Mnemosyne, the goddess of memory. At first, there were three muses, then the Greek poet Hesiod expanded their number to nine: Calliope, Clio, Euterpe, Erato, Terpsichore, Thalia, Melpomene, Polyhymnia, Urania.[ . . . ]

Most modern muses were powerful and often creative women in their own right, like Georgia O’Keeffe (1887-1986) who didn’t just inspire photographer Alfred Stieglitz, but influenced the direction of his art. Salvador Dalí’s wife and muse, Gala, whom he met in 1929, shrewdly tortured her sex-averse and masochistic husband with her flagrant affairs. Suzanne Farrell, George Balanchine’s astonishing dancer-muse, allowed the legendary choreographer to fall in love with her while rejecting his advances, only to marry another dancer the very day Balanchine obtained a divorce from his wife.

There were some famous exceptions to the growing equality between muses and their clients. Picasso met Marie-Thérèse Walter in 1927 on a Parisian street when she was 17 and immediately made her his mistress, sometimes having his chauffeur wait outside her private school to pick her up when school let out and take her to the artist’s studio, where she modeled for countless paintings and sculptures. She later bore him a daughter though he refused to marry her, and killed herself in 1977, four years after Picasso died. [ . . . ] Nowadays muses are hard to find. There have been a few celebrated ones in recent years: the photographer Lee Friedlander’s wife, Maria, whom he photographed over four decades; John and Yoko Ono (mutual muses); painter John Currin and his Botticellian wife, the artist Rachel Feinstein.

Where Have All the Muses Gone? (Wall Street Journal)