Still, as an aging population wrangles with how to gracefully face the certainty of death, the moral and economic questions presented by palliative care are unavoidable: How much do we want, and need, to know about the inevitable? Is the withholding of heroic treatment a blessing, a rationing of medical care or a step toward euthanasia?

A third of Medicare spending goes to patients with chronic illness in their last two years of life; the elderly, who receive much of this care, are a huge political constituency. Does calling on one more team of specialists at the end of a long and final hospital stay reduce this spending, or add another cost to already bloated medical bills?

Dr. O’Mahony and other palliative care specialists often talk about wanting to curb the excesses of the medical machine, about their disillusionment over seeing patients whose bodies and spirits had been broken by the treatment they had hoped would cure them. But their intention, in a year observing their intimate daily interactions with patients, was not to limit people’s choices or speed them toward death.

Rather, Dr. O’Mahony and his colleagues were more subtle, cunning and caring than their own words sometimes suggested.

An Escort for the Dying

They are tour guides on the road to death, the equivalent of the ferryman in Greek myth who accompanied people across the river Styx to the underworld. They argue that a frank acknowledgment of the inevitability of death allows patients to concentrate on improving the quality of their lives, rather than lengthening them, to put their affairs in order and to say goodbye before it is too late.

Dr. O’Mahony, 41, went to medical school in his native Dublin, straight out of high school. He intended to go into oncology. But during training at a prominent cancer hospital in New York, he changed his mind as he saw patients return to the hospital to die miserable deaths, hooked to tubes, machines and chemotherapy bags until the end.

“In Ireland, and I think most other places, it would be very much frowned upon,” he said.

Sandy-haired, a wiry marathon runner, Dr. O’Mahony is the sixth of eight children; his father is a university professor devoted to preserving Gaelic as a second language, and his mother a painter. When he was 3, his brother, who had cerebral palsy, died at age 4. His awareness of his parents’ helplessness, burnished through years of family conversations, helped steer him to palliative care, he said.