There are so many new books about dying that there are now special shelves set aside for them in bookshops, along with the health-diet and home-repair paperbacks and the sex manuals. Some of them are so packed with detailed information and step-by-step instructions for performing the function that you’d think this was a new sort of skill which all of us are now required to learn. The strongest impression the casual reader gets, leafing through, is that proper dying has become an extraordinary, even an exotic experience, something only the specially trained get to do.

Also, you could be led to believe that we are the only creatures capable of the awareness of death, that when all the rest of nature is being cycled through dying, one generation after another, it is a different kind of process, done automatically and trivially, more “natural,” as we say.

An elm in our backyard caught the blight this summer and dropped stone dead, leafless, almost overnight. One weekend it was a normal-looking elm, maybe a little bare in spots but nothing alarming, and the next weekend it was gone, passed over, departed, taken. Taken is right, for the tree surgeon came by yesterday with his crew of young helpers and their cherry picker, and took it down branch by branch and carted it off in the back of a red truck, everyone singing.

The dying of a field mouse, at the jaws of an amiable household cat, is a spectacle I have beheld several times. It used to make me wince. Early in life I gave up throwing sticks at the cat to make him drop the mouse, because the dropped mouse regularly went ahead and died anyway, but I always shouted unaffections at the cat to let him know the sort of animal he had become. Nature, I thought, was an abomination.

Recently I’ve done some thinking about that mouse, and I wonder if his dying is necessarily all that different from the passing of our elm. The main difference, if there is one, would be in the matter of pain. I do not believe that an elm tree has pain receptors, and even so, the blight seems to me a relatively painless way to go even if there were nerve endings in a tree, which there are not. But the mouse dangling tail-down from the teeth of a gray cat is something else again, with pain beyond bearing, you’d think, all over his small body.

There are now some plausible reasons for thinking it is not like that at all, and you can make up an entirely different story about the mouse and his dying if you like. At the instant of being trapped and penetrated by teeth, peptide hormones are released by cells in the hypothalamus and the pituitary gland; instantly these substances, called endorphins, are attached to the surfaces of other cells responsible for pain perception; the hormones have the pharmacologic properties of opium; there is no pain. Thus it is that the mouse always seems to dangle so languidly from the jaws, lies there so quietly when dropped, dies of his injuries without a struggle. If a mouse could shrug, he’d shrug.

I do not know if this is true or not, nor do I know how to prove it if it is true. Maybe if you could get in there quickly enough and administer naloxone, a specific morphine antagonist, you could turn off the endorphins and observe the restoration of pain, but this is not something I would care to do or see. I think I will leave it there, as a good guess about the dying of a cat-chewed mouse, perhaps about dying in general.

Montaigne had a hunch about dying, based on his own close call in a riding accident. He was so badly injured as to be believed dead by his companions, and was carried home with lamentations, “all bloody, stained all over with the blood I had thrown up.” He remembers the entire episode, despite having been “dead, for two full hours,” with wonderment:

It seemed to me that my life was hanging only by the tip of my lips. I closed my eyes in order, it seemed to me, to help push it out, and took pleasure in growing languid and letting myself go. It was an idea that was only floating on the surface of my soul, as delicate and feeble as all the rest, but in truth not only free from distress but mingled with that sweet feeling that people have who have let themselves slide into sleep. I believe that this is the same state in which people find themselves whom we see fainting in the agony of death, and I maintain that we pity them without cause. . . . In order to get used to the idea of death, I find that there is nothing like coming close to it.

Later, in another essay, Montaigne returns to it:

If you know not how to die, never trouble yourself; Nature will in a moment fully and sufficiently instruct you; she will exactly do that business for you; take you no care for it.

The worst accident I’ve ever seen was on Okinawa, in the early days of the invasion, when a jeep ran into a troop carrier and was crushed nearly flat. Inside were two young MPs, trapped in bent steel, both mortally hurt, with only their heads and shoulders visible. We had a conversation while people with the right tools were prying them free. Sorry about the accident, they said. No, they said, they felt fine. Is everyone else okay, one of them said. Well, the other one said, no hurry now. And then they died.

Pain is useful for avoidance, for getting away when there’s time to get away, but when it’s end game, and no way back, pain is likely to be turned off, and mechanisms for this are wonderfully precise and quick. If I had to design an ecosystem in which creatures had to live off each other and in which dying was an indispensable part of living, I could not think of a better way to manage.

[From The Medusa and the Snail: More Notes of a Biology Watcher, by Lewis Thomas]