'The whole story of this lady is a romance, and everything she does," wrote Samuel Pepys of Margaret Cavendish, Duchess of Newcastle.
Earlier that day - intrigued by rumours of the scandalously garish outfits, the bare-breasted appearances in theatre boxes, the black stars that adorned her cheeks - Pepys had joined the crowds that thronged the streets when the duchess's carriage passed, desperate to glimpse the notorious eccentric known as "Mad Madge".
At a time when most women writers published anonymously, under a male pseudonym or not at all, Cavendish (1623-73) put her own name to a vast range of works on whatever fascinated her capacious imagination.
Eager for fame, though dismissed as infamous, she declared herself "as Ambitious as ever any of my Sex was, is, or can be; which makes, that though I cannot be Henry the Fifth, or Charles the Second, yet I endeavour to be Margaret the First". Danielle Dutton's elegant, expansive novel, a sort of fictionalised biography, reaches beyond the myth and bluster to conjure Cavendish's rich inner life.
The sensual portrait is built impressionistically, initially from brief vignettes: nine-year-old Margaret down by the river, inventing an ephemeral civilisation made of the foam bubbles on the surface of the water; the day she starts her periods, when her mother sternly warns her to stop "writing little books" and focus on "beauty and virtue".
Instead, Margaret becomes a royal courtier, then marries William Cavendish, an exiled Royalist and society man 30 years her senior. Her struggle to conceive - the shame compounded by the humiliating treatments forced on her - is balanced by her discovery in writing of the means to escape a conventional existence.
Dutton's exuberant prose, brimming with unexpected phrases and twists, mirrors Margaret's zest for life as she transforms from dreamer to writer, ornament to actor; her pleasure in her work is tempered only by self-doubt as public attention fixates on her body, not her mind.
Dutton's style is as remarkable as her subject; this curious, beautiful novel is a sensitive interrogation of the conflicting attractions of celebrity, femininity, marriage and ambition.