Choosing to become a physician is to sign on for a professional life of extraordinary complexity. Trusted to tend to people in their most vulnerable states, recognized as repositories of experience, wisdom, and skill, physicians are accustomed to our respect and admiration. But in a market-driven world, doctors’ relationships with patients are fraught with the possibility of something going terribly wrong. When their diagnoses are flawed, their drugs don’t heal, or their surgeries cause complications, doctors fall with a resounding thump from the pedestals on which we have hoisted them. To practice medicine is to be revered frequently and disdained occasionally. Doctors need strong egos, but they need humility, too, and an appreciation of how limited medical knowledge remains.

Now two eminent doctors, Jerome Groopman and Sherwin Nuland, have attempted to get down on paper what medical practice has taught them. Both presume — correctly — that many people are interested in reading about doctors’ insights on life, death, and the treatment of disease. Dr. Groopman’s “How Doctors Think” (Houghton Mifflin, 320 pages, $25) is by far the more successful book because he pulls back the clinical curtain and exposes how doctors make decisions about patient care. The result is an engrossing work filled with dozens of case studies, and written in a personable style by a renowned but still humble physician not afraid to admit his own mistakes.

Dr. Groopman, a staff writer for the New Yorker and a professor of medicine at Harvard, focuses on the different ways a doctor can go wrong. He tells heroic stories of laser-sharp diagnoses, but the errors in practice engage him more. In an absorbing chapter on cancer treatments, Dr. Groopman describes cases in which oncologists cleave closely to data on chemotherapy and refuse to customize care for individual patients. But he also cites doctors who believe any full assessment of a patient must factor in the individual’s personality, goals, and history. While Dr. Groopman acknowledges that diverging from standard treatments can lead to unnecessary suffering, he also believes closing down those avenues deprives patients of real options and shows doctors to be overly anxious about failure.

But other feelings beyond fear can interfere with a doctor’s judgment. One story Dr. Groopman tells about himself involves his relationship with a patient, a young English professor whom he liked and admired. When the man, who suffered from bone cancer, was under Dr. Groopman’s care, the doctor found himself spending extra time at his bedside talking about their mutual interests in James Joyce and long-distance running. When, after three courses of chemotherapy, the patient began to suffer from a low-grade fever Dr. Groopman tried to discover its cause. Examining the exhausted man, he found nothing alarming, but later in the day the patient’s fever spiked dangerously and he was dispatched to the Intensive Care Unit. A resident told Dr. Groopman that the source of the infection was now clear, an abscess on the left buttock, which was present six hours before, when Dr. Groopman had examined him. Out of sympathy for his patient, unwilling to inconvenience someone he had begun to regard as a friend, the doctor had “broken discipline” and shortened his examination. The young man survived, but it was a sobering lesson for his physician.

The humility, warmth and richness of Dr. Groopman’s accounts finds no echo in Dr. Nuland’s “The Art of Aging: A Doctor’s Prescription for Well-Being” (Random House, 286 pages, $24.95). The Yale surgeon, best-known for “How We Die: Reflections on Life’s Final Chapter” (1994), returns here to dissect the last years of life, but he writes in a wandering and self-important way, and comes to no fresh conclusions about how to successfully navigate old age. The book is full of such platitudes as “We require relatedness to others, both as individuals and as groups,” and “We must treasure one or more others, and in the treasuring be treasured.”

Dr. Nuland does interview a number of older people, and one of the book’s few interesting sections concerns Michael DeBakey, the pioneering cardiovascular surgeon, among the first to perform coronary artery bypass surgery. Dr. De-Bakey, who will turn 100 years old next year, performed operations well into his 90s. He tells Dr. Nuland that his drive and prodigious achievements sprang from the gratification he found in doing something important for people. “Life, after all, is the greatest thing we have, and doctors are in a unique position to maintain it, to save it, to give it,” Dr. DeBakey says. Dr. Nuland uses this insight to underline how crucial it is for older people to use their own abilities to help others. No doubt this is true, but it’s also easy for a doctor to prescribe. Dr. Nuland doesn’t seem to appreciate that for the vast majority us, helping others is an add-on to our working lives. For doctors, feeling useful, helpful, and needed comes with their choice of profession. It is the psychological payoff that compensates for the frustrations and the risks of practicing a still imperfect art.

Ms. McHugh is an editor at Time Inc.