When novelist and intellectual Susan Sontag was diagnosed in 2004 with myelodysplastic syndrome, a precursor to a rapidly progressive leukemia, she had already beaten the odds of dying twice. Most remarkably, in 1975 she survived stage IV breast cancer partly by opting for a radical and arduous immunochemotherapy treatment. From this experience came her essay "Illness as Metaphor," which examined the cultural myths and euphemisms that surround cancer and other diseases.

But when faced with her final, virtually incurable disease at the age of 71, she refused to accept the possibility of death -- and refused to let those close to her accept it in her presence. The phrase "quality of life" made her incredulous. She was determined to fight death at any cost -- including the cost to her son, David Rieff. Though always contemptuous of false optimism in her intellectual life, Sontag enlisted Rieff in a campaign to misconstrue facts in order to reassure her that she would survive a grueling and costly bone marrow transplant that was all but doomed to fail.

Swimming in a Sea of Death is Rieff's poignant account of his duplicitous role in the last nine months of his mother's life -- and a meditation on the questions that still haunted him two years later. What role should adult children play in their parents' final months? Does a parent owe a child anything in how they choose to die? And who, exactly, is a "good death" for?

Q. What do you wish you had known when you were helping your mother through the last months of her life?

A. One of the things that I took out of this experience is that it's incomprehensible until you're in it. Nothing can prepare you in the deepest sense. Talking about it, thinking about it, abstractly trying to conceive of it, even dealing with it with people who are less close to you -- none of those things seem in the end to be central to what you have to do. One of the great difficulties of this situation is that in some way we all have to live through it, both as helpers and then ourselves as we die, but there's no class for learning it, and there can't be.

Q. Your mother's death left you haunted by the idea of whether you did the right thing. When do you think you should have been more honest?

A. At the beginning, because the chances were so slim of the treatment working and she was going to suffer so much. But I got over that fairly quickly, because she was so afraid of dying that I thought it was better not to be honest with her.

Q. As a result, you were never able to say good-bye to her. Would that have been important to you? Would it have been important to her?

A. It would have been terrifying to her, but it would have been important to me. That's in a way what the book is about: I think the interests of the loved one and the interests of the dying person are often at odds, and you have to defer to the dying person. But it's not easy.

Q. It seems that your mother was almost charging you with saving her life. Do you think she ever thought about the difficult role she was putting you in, as her son?

A. I don't think it was possible for her, given her fear and her belief that she could live. She wasn't that kind of person. Would it have been easier for me? Sure. But then it would have been harder for her. I wasn't conscious of thinking about my own interests in this. I made a decision to abet this belief of hers, and to help her with it, because it was clear what she wanted. So I danced around it like in debating school, where they give you a theme and it doesn't matter what you personally believe; what matters is that you can figure out some way of making a case. Or, like a lawyer, I was making a brief for her survival, and that's what she wanted.

Q. In the book you write, "In being in some sense part of my mother's emotional life support, I found myself to be on emotional life support." What did you mean by that?

A. What I meant was that in order to be of help to her, I had to not think about what I knew. Not thinking about what I knew meant, to some extent, not thinking, because if I were really thinking all the time and allowing myself to be fully alert, I just never could have pulled it off.

As a journalist, I covered the Rwandan genocide, so it's not as if I haven't seen terrible stuff. But it's different when it's not your mother. And even there, I remember being in a hospital during the cholera epidemic in eastern Zaire in 1994, and all these terrible things were happening to people, and I'd stare at them but not see them -- look at them but somewhere be not looking at them. I feel I had to do that in my mother's case.

I do think it helped me in one sense. In order to do what I did, I had to put something I wanted -- which was to have certain conversations with her -- aside. In order not to be upset by that, I had to not think. And I don't believe that's so rare.

At the University of Washington hospital [where Sontag received a bone marrow transplant], there's a family room, but it's always crowded, and a lot of "stuff" spills out into a sort of common room. And so you hear all this stuff. You don't want to, but where can you go? You're sitting there watching something stupid on the TV or you're pretending to read the newspaper, and you hear these conversations -- doctors would come out and talk to the families. I heard a lot of people who seemed to be shutting it out for the sake of the person down the hall who had all the tubes in her. I saw other people who seemed to be making similar decisions to mine. It seemed to me that a lot of people I met in these waiting rooms were going numb.

Q. You write that in some ways it was easier when doctors didn't tell patients the truth about a bad prognosis. And in your case, everyone -- even the patient herself -- conspired to withhold the truth. From what you describe, it seems that people frequently engage in that kind of effort.

A. I agree with you completely. And I think good doctors learn a way of saying the truth that's not understood as the truth. So they don't lie, but they manipulate the conversation so that in some way they can give the person false hope, if that's what the person is looking for. For people who want to have real conversations with their loved ones before they die -- about the past, about their relationship, and also to express feelings -- the lies are an active disservice.

Q. You believe that your mother was "entitled to die her own death," but some have criticized her way of dying. One doctor at the Fred Hutchinson Cancer Research Center wrote to you that the "vast majority" of people in her situation give up the fight, if only to make the "last bit of limited time memorable for those they'll leave behind." Do you think he was right?

A. Not only do I think he's wrong, but when I went back to New York and spoke to Stephen Nimer, her principal doctor at Memorial Sloan-Kettering, and Marcel van den Brink, who is now the head of transplantation at Memorial Sloan-Kettering, they said, "Well, that's not our experience. Some people are the way that doctor describes it, but many aren't. There are many people like your mother." Lots of people who've read this book told me they had the same experience with a loved one. I just don't think it's atypical.

Q. Most caregivers, of course, would like to make their parents' death a "good death." You're saying that may not be possible. Do you think people want to hear this?

A. I think they do when it happens to them.