THE AUDIENCE IS SPELLBOUND. As a haunting melody fills the Sydney art gallery, performance artists Theresa Byrnes appears from the wings, seemingly gliding in the arms of two barrel-chested carriers. Byrnes, who is unable to walk and has restricted movement in her arms, sits cross-legged and gazes serenely ahead as she digs her hands into a ceramic urn, pulls out a dollop of black ink and smothers her beautiful face in it. Next, she cuts off locks of her hair and swishes them about in paint on the canvas before her. A she lies back and immerses herself in the paint, the artist becomes part of the canvas itself. The starkly simple performance, called Nest, lasts for 20 minutes. "No-one took their eyes off her," says Greg Weight, a fine art and portrait photographer who over a 40-year career has shot a long line of esteemed artists including Lloyd Rees, Bret Whiteley and Donald Friend.

Diagnosed at 17 with a rare degenerative disease of the nervous system called Friedreich's ataxia (FA), which has gradually robbed her of movement, balance and sensation, Byrnes has spent the past 23 years in a fast, furious charge of self-expression. Her work, which ranges from abstracts to portraits, from miniatures to spectacular four-meter giants, has been exhibited in some of the world's most prestigious galleries, and she has won two Pollock-Krasner art awards. But it's been her controversial performane pieces that have attracted the most newspaper space both here and abroad (she has been based in New York since 2000).

"Theresa was born to be an artist," notes Weight, who has known the 40-year-old since 1999, when he began photographing her work. "She made the decision to be an artist before she was diagnosed with FA - and she's never let the disease hold her back. Not for one moment."