On Feb. 6, 2000, 67-year-old Guy Waterman — naturalist, musician, scholar, outdoorsman, respected author and devoted husband — decided to climb a New Hampshire mountain, lie down on the cold stones and die overnight of exposure. An experienced mountaineer who had written several books on wilderness issues, Waterman embarked on this final hike wearing only a thin jacket and carrying a note (almost like a schoolchild’s permission slip) reading: ”Do not take special efforts to save life. Death is intended.” But why?

The fine journalist Chip Brown, in his searching, intelligent biography, ”Good Morning Midnight,” has taken up the brave task of trying to answer this question. We are generally taught to allow the dead to rest in peace, but somebody had to tell Waterman’s story. When any man chooses to die in such a grandiose fashion, it’s as though he had requested — indeed demanded — that we examine his death thoroughly. Suicide, while arguably humanity’s most private act, often becomes after its completion a public investigation, as the living struggle to answer all the burdensome questions the dead man himself left behind.

Waterman’s own explanation, offered in suicide notes to friends, was that he killed himself to avoid suffering the ”prospects of aging, with all its discomforts, indignities and limitations.” Yet he was healthier than most men half his age. Still, many judged his decision heroic. As one Vermont newspaper put it: ”Few of us get to live the lives we really want to lead. Even fewer of us end our lives in a meaningful, dare we say positive, way. . . . Guy Waterman serves as a great lesson to all of us. Although the loss of a great man will be keenly felt by both his neighbors and his readers throughout the world, we can all take comfort in the fact that he passed away with the peace and dignity he showed throughout his life.”

Grand words, but . . . really? Brown weaves together an alternative view of Waterman — a man who was indeed brave and brilliant, but far from peaceful. (”Caliban,” Waterman named his darkest inner demon.) The youngest son of a distinguished New England family, Waterman was a peevish child who grew into a defiant teenager, eloped at 18 largely to shock his father, and then — far too young — was a father himself. Waterman soon loathed his wife but remained married for the sake of his three sons (and 1950’s suburban protocol). He became a hotshot speechwriter for the Republican Party, but also, in time, a bitter, desolate alcoholic.

Then something happened to Waterman in 1963. Midlife, he discovered mountain climbing, the way other drunks discover Jesus — as a revelation bringing dazzling new birth. ”I was swept off my feet,” he later wrote of this wilderness epiphany. ”Mountains and mountain climbing dawned on my drunken, shamed, lonely life like a beacon of hope.” Within a few months he was sober. Within a few years he’d divorced and moved to a mountain cabin, eventually marrying a lovely woman named Laura (a true soul mate and fellow mountaineer), and was trying to repair relations with his teenage sons by teaching them rock climbing. The White Mountains became Waterman’s backyard and he — this former Republican suburbanite — their most dedicated caretaker and chronicler. ”I shall shamelessly boast,” he wrote, ”by saying I don’t think anyone knew the White Mountains so well as I. . . . Talk about joy, pride, emotional riches!”

He always broadcast his transformation as a valiant success story, but there were still secret patches of quicksand all over Waterman’s psyche, dangerous places where he often fell through the surface of his own self-mythologizing into bottomless despair. Waterman was always prone to darkness, but something permanently collapsed in him after he lost all three of his sons. Bill, the eldest, slipped away into drug-addled oblivion and disappeared somewhere in Alaska, presumed dead. Johnny became one of the most famous mountaineers of his time, enduring an epic 145-day solo ascent of Alaska’s Mount Hunter in 1978. But the achievement brought Johnny nothing but existential disenchantment (surviving the impossible climb, he said to a friend, only meant that ”nature wasn’t as raw as everybody wanted to believe”), and, two years later, fresh out of a mental hospital, he wandered alone up avalanche-ridden Mount Denali, never to be seen again. Jim, the youngest, vanished from his father’s life in a more traditional manner; he cut off nearly all contact.

Waterman never really addressed these tragedies. Instead, he retreated into the mountains, the only place he’d ever found solace. (”The trail was like a rosary,” Brown writes, ”and climbing it Waterman’s way of praying.”) So one can imagine his terror at the prospect of aging, of becoming physically unable to climb, therefore — in his mind — unable to pray. Wouldn’t it be better to die of exposure alone on a mountain ridge than risk being exposed to one’s unexamined emotional pain?

Brown circles such questions with exquisite poise, trying to make out the truth through a surrounding miasma of sorrow, denial and aggrandizement, even when it means pressing Waterman’s friends and family to psychologically scrutinize a man they might prefer simply to deify. And nobody is more challenged by this scrutiny than Laura, Guy’s second wife, who cherished her husband — so much so that, Brown writes, she apparently didn’t try to stop his suicide mission once he’d informed her of his intent, many months in advance. Indeed, as Laura wrote to a friend, she was ”part of the process” of her husband’s mental preparations for death — a revelation that adds only further layers of questions to an already complex story.

Was Laura a massive enabler, as some friends later wondered? Had this kind, intelligent woman been seduced by her husband’s propaganda, accepting his view that after a vigorous man has turned 60 a decision to choose suicide was merely ”a sensible option to take”? When friends later wondered why Waterman hadn’t sought help for his depression, was it Guy the dramatic speechwriter who orated through Laura’s voice when she replied: ”Medicate his demons? . . . Better to live with the full blast of his terrors than soften those sharp edges”? Or was there some more mysterious emotional comprehension at work here? After all those private years together in a cabin, had their marriage grown so deep that Laura, almost at a molecular level, understood something about Guy that no outsider could ever see? Was her participation in his preparations for death an act of negligence? Ignorance? Or otherworldly devotion?

”I never stopped loving Guy,” she confides to Chip Brown. ”Why was that?”

Brown is too wise a writer to attempt an answer. He merely presents this statement along with every other possible facet of Guy Waterman’s perplexing story, then gets out of the way. In the end, Laura’s question, like so many others, will have to remain adrift.

Elizabeth Gilbert’s most recent book is ”The Last American Man.” She is a writer at large for GQ.