‘Your favourite virtue?’ ‘I don’t have any: they are all boring,’ wrote the 21-year-old Camille Claudel in a Victorian album belonging to an English friend in 1886. The remark perfectly matches the photograph of the aspiring sculptor taken two years earlier by César: childlike, sullen, attitudinous, beautiful.

Claudel was in England on a break from working in Auguste Rodin’s studio, where she had been taken on as an assistant in 1884. She had met Rodin through her mentor Alfred Boucher, who discovered her precocious teenage talent on a visit to his hometown of Nogent-sur-Seine in the 1870s, and continued to supervise her subsequent studies in Paris. When Boucher left for Florence in 1882 he placed his protégée in the care of his friend Rodin who, needing assistants for ‘The Burghers of Calais’, asked her to join his atelier. In this all-male environment she reduced and enlarged maquettes, made studies for commissions, learned to carve marble and quickly became the master’s right-hand woman. It would have been the perfect working relationship if Rodin — 24 years her senior — hadn’t fallen in love with her.

He was 43 and she was 19 when they embarked on a tempestuous seven-year affair. There were furious bust-ups, promises of marriage and at least one abortion, but Rodin lacked the will to leave his long-term partner Rose Beuret, an uneducated former model he kept hidden away from his cultured friends. According to one of them, Octave Mirbeau, Beuret existed ‘in complete ignorance of what he does’, whereas Claudel gave Rodin ‘the happiness of being always understood’.

For Claudel the happiness was more equivocal. Cut off by the scandal from her bourgeois family and financially dependent on Rodin, she was cast into the shadow of the master with whose work hers was inevitably compared. In the 1890s she made a break for freedom, at the risk of sacrificing her protector’s support. ‘For a man, being a sculptor is a constant challenge to common sense,’ her brother Paul Claudel would write years later, ‘for an isolated woman, especially one with my sister’s character, it is a pure impossibility.’ In increasing isolation and penury, she developed paranoid delusions about Rodin, convinced he was trying to kill her to steal her ideas. In 1913, aged 48, she was referred to an asylum. ‘I have fallen into an abyss,’ she wrote. ‘I live in a world so curious, so strange. Of the dream that was my life, this is the nightmare.’ She would spend the last 30 years of her life in confinement, refusing ever to touch clay again.

How good was Camille Claudel? A new museum in Nogent-sur-Seine, an hour from Paris, gives us a chance to find out. As well as housing 40 of her sculptures, the Musée Camille Claudel, incorporating her former family home, sets Claudel’s work in the context of French 19th-century sculpture from the collection of the town’s former Dubois-Boucher museum, now relocated to the new museum’s ground floor. With the exception of a touchy-feely female torso by Aimé-Jules Dalou and a mischievous nymph with a passel of faun brats by Gustave Doré, the downstairs displays only serve to confirm how dull and lifeless the so-called ‘Golden Age’ of French sculpture was. ‘We must unfreeze sculpture,’ Rodin said. Upstairs, it thaws.

A creation myth of Claudel’s career tells how the director of the École des Beaux-Arts, Paul Dubois, exclaimed on seeing her teenage sculptures, to her mystification: ‘You took lessons from Monsieur Rodin!’ When she did take lessons from Rodin the influence became obvious but, along with the similarities, there were differences. Claudel’s handling is rougher, her movement more hectic. It’s her passionate nature that imbues ‘L’Éternelle Idole’ (1889), conceived by Rodin at a crisis in their affair. Her troubled surfaces can sometimes verge on the expressionist: the furrowed and pitted ‘Tête de vieillard’ (c.1890) anticipates Giacometti’s portraits by half a century.

She had a broader spectrum of moods than Rodin. On the one hand there was the quiet vulnerability of ‘La Petite Châtelaine’ (1895–96), the bust of the little girl with tousled marble ringlets that gave Rodin — who didn’t carve his own marble — ‘the impetus for competition’. On the other hand there was the wild intoxication of ‘La Valseurs’ (1883–1905), represented here by four small casts whirling around a circular plinth as on a mini-dance floor. Claudel’s hopes of winning public funding for a larger marble version of this sculpture collapsed after the art inspector who visited her studio in 1892 was disturbed by ‘the closeness of the sexual organs… rendered with a surprising sensuality, which is considerably reinforced by the absolute nudity of all the human details’. She tried dressing the figures, to no avail; even clothed, their abandon seemed indecent.

Sex, more than simply gender, was an obstacle to her success. At a time when the École des Beaux-Arts was still closed to women, it was hard enough for a female artist to gain official acceptance without her trespassing on the male turf of sexual ecstasy — and ecstasy was what Claudel excelled at expressing. Still, compared with Rodin’s nudes, hers were demure. While the knees of Rodin’s ‘Femme accroupie’ (1881–82) are shamelessly splayed to expose her pudenda, Claudel’s ‘Femme accroupie’ (1884–85) preserves her modesty. There’s a similar innocence about her ‘L’Abandon’ (1886) compared with Rodin’s ‘L’Éternelle Idole’ (1889). ‘L’Abandon’ was a scaled-down version of ‘Sakountala’, the first large sculpture she had shown, to critical acclaim, at the 1888 Salon. Unable to secure a public commission for a marble, she eventually donated the plaster to the Chateauroux Museum in 1895, only to find she couldn’t give it away — it was returned after a local outcry. The museum’s life-sized bronze version, cast in 1987 from the damaged plaster, is missing three arms and a foot.

In the end, Claudel’s protracted struggles to win public commissions wore her down. When a private patron paid for a marble version of her ‘Perseus and the Gorgon’ in 1897, she expressed her bitterness by giving the Gorgon her own features, and a squint. The killer blow was the cancellation of a state commission for her most ambitious and personal work, ‘L’Age mûr’. Showing an older man being dragged away by a crone from a pleading young woman, it was blatantly autobiographical. The commission was already in the bag when the plaster was shown at the 1899 Salon, where Rodin saw it. Without explanation, the commission was suddenly withdrawn. That was when the paranoid delusions started. Claudel’s few surviving small sculptures from the 1900s were editioned, at a loss, by her faithful dealer Eugène Blot; the others she smashed.

Was Camille Claudel her own worst enemy? With a different personality she might have succeeded, though not on her terms. In the male-dominated milieu of her day she was a freak, even to an admirer like Mirbeau — ‘something unique, a revolt of nature: a woman of genius’.