Everyone knows that we're all dying. But would you really want to know that death was imminent?

There was a time when news of this kind was kept from patients by doctors and even spouses. Recently someone we know, discussing a terminally ill friend, expressed the wish that she herself might be spared the knowledge (when her time comes) that medicine has nothing more to offer, so she could go on with normal life.

Of course the dying have always known, many of them, despite efforts to hide their fate. I believe that Chick Austin, the museum impresario who helped bring modernism to America, knew that the end was near even though the fact was kept from him by everyone. Perhaps he kept up the charade as much for the others as they did for him.

Today, in the face of some potentially fatal disease, it's hard not to know, and patients seem to do better when they take control of their own medical destiny by studying up and making informed decisions. Yet I began to wonder if there was not a mechanism whereby our friend could be granted her wish if ever she gets into such a situation.

Many of us have a health-care proxy and durable power of attorney in case we should become seriously ill. Might it not also be possible to dictate in advance how much we want to be told about a dismal medical prognosis? Perhaps we could designate a spouse to receive the full skinny, while we are allowed to remain in the comforting shadows of self-deception. This would give our friend the chance to have the end of life she seems to want when her time comes (may it be a long way away).

We all use techniques to constrain our future choices, much as Odysseus did by having his men tie him to the mast so he could hear the Sirens but not succumb to their lethal song. And we sometimes use these "precommitment" tactics to insulate ourselves from knowledge we don't want. (There's a pretty interesting book called Forbidden Knowledge on this very subject, by Roger Shattuck, in which the Sirens' song is described in just these terms: Odysseus might be said to want the truth but not the consequences.) Who knows, maybe a lot of what we do every day has this larger purpose: to fend off the knowledge we'll soon die.