Marion Halligan has been talking and writing about her daughter Lucy since she died 18 years ago

From lifelong friends and passing acquaintances, the letters were filled with stories and anecdotes about Lucy. People took the trouble to write down these stories, beyond the mere stock condolences.

Halligan was stunned, and still is today, nearly 18 years later.

Lucy was 38 when she died. She was beautiful, wise, witty, a warm and loving daughter and sister, a loyal friend and, as it turned out, the kind of person you didn't forget, even after a fleeting interaction.

Halligan has been talking and thinking about Lucy more or less constantly ever since she died. The fact of her, the beauty of her life and her presence, the lament of her early death.

Her new book, Words for Lucy, is these last 18 years of thoughts on the page. She began it, in a way, when Lucy died, and she was trying to understand how she could be so comprehensively gone. She was, you see, still so very present.

The book is filled with memories, impressions, descriptions - the way Lucy looked, conversations they had, trips away, memorable meals, things she bought and loved, gifts she gave that are now forever cherished. The level of detail is almost photographic; Halligan is a committed recorder of the minutiae of life.

"I'm a great believer in details - I think it's details that make people believe what you say," she says.

"If you don't give details, especially when you're writing a novel, who's going to know whether you're telling the truth or not?"

It's been six years since we last sat in Halligan's bright, cluttered kitchen, in the inner-north Canberra house she's lived in now for 60 years.

Things have changed. Back then, we were talking about Goodbye Sweetheart, her 11th novel and 22nd book. Since then, she has grown unwell. She's on dialysis now, after a stroke; it's a bore and a chore, but something that's keeping her going.

She's now 82, and jokes that she's thinking of retiring. Going through old memories - the way you would pull photographs from a box - has been a reminder, she says, of how busy she once was.

"I look at the amount of energy I had then, rushing around and doing things, and these days, you know, I don't move from my walker," she says.

"I either sit on it or walk around with it."

All the same, her writing is as sharp and vivid as ever. Words for Lucy, her 23rd book, is sad, but exquisitely so. The cover shows a smiling photo of Lucy as a girl, overlaid with spangles of light - a reference to the mirrorball she once gave to her mum. She remembered Halligan saying, on multiple occasions, that she'd always wanted one for the house.

It hangs, now, in her study, catching the afternoon light, much like the Lucy who lives in so many memories.

Born with a heart defect, she had a life that was unusually precious, and circumscribed by her condition. In the days after her birth, doctors advised Halligan and her husband that they might want to have her christened, if they believed in doing that kind of thing.

They did, "maybe to keep terror at bay; we knew what his words meant", Halligan writes.

There were many years of illness, and worry, and operations. Of close proximity with the hard, chilly world of hospitals and surgeons and other families, much worse off than your own, but still.

But there was also much joy. Lucy's life was, on the outside, a small one; she never married or had children, or even moved out of home. She couldn't work, her days weren't very varied. But she also lived a rich life filled with small pleasures.

"She could not do very much, so things were a comfort and an interest," Halligan writes.

Lucy loved reading, and watching films. She loved music and plays, she adored shopping, especially when it involved buying gifts for others.

It was a life rich in detail, the kind of life that leaps off the page, with the right spark beneath it. It's the detail that makes for great literary material, and is the hallmark of many of Halligan's books, which is why writing about her has always been an inevitability.

Towards the end of Lucy's life, things got harder, and her health deteriorated. A heart-lung-liver transplant was on the cards, but Lucy wanted none of it. Previous operations - one at the age of nine, another at 21 - were horrible and arduous, although groundbreaking. Many children had died of her condition.

But Lucy didn't want to do it again. So when she died, suddenly, and far too young, it seemed to Halligan to be something of a statement, if not a conscious one.

It was James, Lucy's younger brother, who found her. She had simply taken a daytime nap, from which she didn't wake up; the cat was curled up beside her. Halligan says James has never truly recovered.

"It sort of got too hard - James doesn't agree with me about this, as I said in the book - and she just lay down and then died, but I think she knew what she was doing. Very subconsciously, not at all consciously."

She says there would have been years of decline and suffering ahead. "She didn't want that, she wasn't going to have it," she says.

In this way, Lucy had lived her life - and so had Halligan - under a kind of shadow. But because Lucy was so delightful, it wasn't a dark one. She emanated light, this much was clear from the messages that came after her death.

"She'd have been astounded at the number of people who wrote to me and gave a little narrative," she says.

"I thought, this is terrific, Lucy would never have guessed that she touched so many people's lives."

But losing her was unbearably hard, even though it could easily have been so much earlier, and her life so very different. Halligan writes about meeting a family while spending time with Lucy at a clinic in Melbourne - an older couple with a daughter in her 30s, except that developmentally, she was no more than a baby in nappies, unable to communicate.

There are so many things life can serve up, and the thing to do is find the beauty in it all, just like Lucy did.

The book also contains other sadnesses; her husband, Graham Halligan, died of cancer in 1998. Her two younger sisters, Brenda and Rosie, are also gone, a fact that makes her "pretty cross", although she devotes hardly a paragraph to this. It is, she says, too hard to delve into, not least because she no longer has anyone to back up her family's memories.

But Lucy has never left her, and this book is filled with the details that made her who she was. In this way, literature can elevate details beyond the mundane, they're what made her life so much bigger.

But there was no need for any artifice to the narrative, other than to pull out memories one by one and commit them to the page. It's not in chronological order, and memories sometimes surface unbidden while thinking of other things.

But this, she says, is how we reflect on life.