The two books arrived on my desk within days of each other. Two books that got down to the heart of the matter to the essential muscle of life. Each was about coronary disease and each was about love -- the double role and meaning of this vital organ.

In the first, "Heartsounds," Martha Weinman Lear chronicles in honest detail and language life with her 53-year-old doctor husband, from his first attack through his slow, unwilling descent into death.

It is painfully vivid, pulsating with his strength and illness, fibrillating with his powerlessness and their mutual pain.

The second, "Thursday's Child," by Victoria Poole, is plainer and more upbeat from the cover to the conclusion. This mother writes about her 17-year-old son, whose heart disease led to a transplant.

The two stories end differently. Today Dr. Harold Lear is dead. Sam Poole is now a sophomore at Stanford, living with 50 medications and their endless side effects. "When you consider the alternaive," he says, "that's not much."

But what struck me most was not the different endings but the similar feelings. At some moment, each family desperately wanted its doctors to "Do Something!" As martha Lear wrote, "I cannot make peace with it. I believed that I could but I cannot. Simply to stand by and let his heart, this part that should be a replaceable part, keep slowing down, fizzling out: and then he is gone."

I was sensitive to this, I'm sure, because a few weeks ago the Massachusetts General Hospital decided Not to Do Something, not to do precisely what had saved Sam Poole, precisely what Martha Lear grasped at: heart transplants.

The MGH -- satirzed as "Man's Greatest Hospital," characterized often as the most prestigious hospital in the world -- made a difficult and influential decision not to do heart transplants, because "in an age where technology so prevades the medical community, there is a clear responsibility to evaluate new procedures in terms of the greatest good for the greatest number."

The decision was surprising for many reasons. In medicine, doctors are taught to respond to the pain of the patient in front of them. To Do Something for one Harold Lear, one Sam Poole. At medical reasearch centers, the elite often prefer that "Something" to be "interesting" and innovative, and transplants are both. Often doctors have adopted new procedures first and worried about the consequences later.

Furthermore, the transplant operation is not as risky as it was in 1967 when Dr. Christiaan Barnard kept his first patient alive for 18 days. Today at Stanford University, whre the heart team has the most experienced and extensive program, 65 percent of the carefully screened transplants live a year; half are alive after five years.

So, when the MGH talks about the greatest good for the greatest number, and turns away from transplants, it is a neon sign of change. It is a blinking announcement of the arrival of the Medical Age of Limits.

The dialogue about "resources" -- about allocating time and money and people -- is a dialogue about short supply. We have stopped believing that we can do everything -- in science, in family life, in government, in industry -- and have begun talking about choosing. This is one of medicine's tough choices.

Heart transplants are as limited as heart donors. We can only "harvest" an estimated 1,000 hearts a year for an estimated 15,000 to 75,000 potential patients. Should we then spend $100,000 for one year of life for a successful transplant? How do we comparison-shop the price of that life versus others that might be saved?

Should we use our resources to give a Sam Poole a new heart, or perhaps to improve the procedures and care given to a Dr. Harold Lear? Should we concentrate on giveing a Dr. Lear more quality care at the outset, or in providing him with the transplant he finally requested at the end? Is it moral not to do everything we are able to do?

The questions that responsible medical people are dealing with have no right or wrong answers. Increasingly, they have to make judgment calls, close calls. And the answers will course through the lifelines of very real people like the Lears and the Pooles.