In our quest to live life to the fullest, most of us have only a vague idea of what will happen to us when the people we love, the people closest to us, die. Sure, we know that death is inevitable for us all somewhere far off in our wished-for future. So we draw up wills and provide for the "rainy day." And we expect that there will be a process called "grieving." But as my own late mother used to say, repeating the Irish wisdom, "We'll deal with it when we have to."

THE YEAR OF MAGICAL THINKING by Joan Didion is her memoir of what she went through in dealing with the unthinkable. On December 30, 2003, Didion and her husband, writer John Gregory Dunne, returned home from the hospital where their only daughter, Quintana Roo, lay in a coma, suffering from severe pneumonia and septic shock. While sitting down to dinner, Dunne had a massive fatal heart attack. They were 31 days shy of their 40th wedding anniversary.

Didion begins this book with the simplest of words: "Life changes fast. Life changes in the instant. You sit down to dinner and life as you know it ends. The question of self-pity."

Quintana would spend 24 days in intensive care after her father's death. Two months later, she collapsed and was rushed into surgery after developing a life-threatening hematoma on her brain. (Sadly, Quintana passed away from an abdominal infection in August. Asked by the New York Times if she would change the manuscript to include her daughter's death, Didion replied, "It's finished.")

Two such catastrophic events happening almost simultaneously would be enough to test the endurance of anyone. And, indeed, Didion writes that this period "cut loose any fixed idea that I had ever had about death, about illness, about probability and luck, about good fortune and bad, about marriage and children and memory, about grief, about the ways in which people do and do not deal with the fact that life ends, about the shallowness of sanity, about life itself."

Writers write. It is the way we decode and make sense of that which often does not make sense. Didion explains, "In time of trouble, I had been trained since childhood, read, learn, work it up, go to the literature. Information was control."

She discovered that the literature on grief, going back to Freud in 1917, is relatively sparse for such a universal ordeal. When told at the hospital that her husband was dead, a social worker described her reaction as being that of a "cool customer," as if that was somehow reassuring. Didion writes, "I wondered what an uncool customer would be allowed to do. Break down? Require sedation? Scream?"

What followed for her was a year of magical thinking, an attempt to change the narrative by an act of will. She couldn't throw out John's shoes simply because he would need them when he came back. "Grief turns out to be a place none of us know until we reach it," she writes. "We do not expect to be literally crazy, cool customers who believe that their husband is about to return and need his shoes."

Memory turned into a "vortex" that could suddenly sweep her away. And here we find Didion's powerful descriptive writing and superb eye for detail. She drives past an LA movie theater and suddenly it was 1967, and she and John are at the premiere for The Graduate. Or she recalls buying her "short white silk" wedding dress in San Francisco at the exact same time that JFK was being assassinated in Dallas.

Didion, author of five novels and seven works of nonfiction, is one of America's greatest writers and essayists. Her two collections of essays about the 1960s, SLOUCHING TOWARDS BETHLEHEM and THE WHITE ALBUM, are essential reading for anybody who wants to understand how America came apart during that turbulent decade. They also should be read by anyone interested in good writing and journalism. Didion is a true master of the craft.

THE YEAR OF MAGICAL THINKING is Didion at her best, covering her most painful story. And she answers "the question of self-pity" by not engaging it. It is impossible not to feel overwhelming sadness after losing the person you loved and spent virtually everyday with for 40 years. But she brings to her loss her journalistic honesty and the ability to search for and find the deeper truth, no matter how unsatisfying that truth may be.

And in so doing, she not only manages to liberate herself from her year of magical thinking but also to provide something of a guide for the rest of us as well. In addition to being a wonderful memoir, this book is an invaluable meditation for that time when the far-off future suddenly becomes now and the rainy day turns into a deluge.