Atul Gawande gave the commencement speech at Stanford’s School of Medicine last week. Here is what he told the graduating class.

Many of you have worked for four solid years—or five, or six, or nine—and we are here to declare that, as of today, you officially know enough stuff to be called a graduate of the Stanford School of Medicine. You are Doctors of Medicine, Doctors of Philosophy, Masters of Science. It’s been certified. Each of you is now an expert. Congratulations.

So why—in your heart of hearts—do you not quite feel that way?

The experience of a medical and scientific education is transformational. It is like moving to a new country. At first, you don’t know the language, let alone the customs and concepts. But then, almost imperceptibly, that changes. Half the words you now routinely use you did not know existed when you started: words like arterial-blood gas, nasogastric tube, microarray, logistic regression, NMDA receptor, velluvial matrix.

O.K., I made that last one up. But the velluvial matrix sounds like something you should know about, doesn’t it? And that’s the problem. I will let you in on a little secret. You never stop wondering if there is a velluvial matrix you should know about.

Since I graduated from medical school, my family and friends have had their share of medical issues, just as you and your family will. And, inevitably, they turn to the medical graduate in the house for advice and explanation.

I remember one time when a friend came with a question. “You’re a doctor now,” he said. “So tell me: where exactly is the solar plexus?”

I was stumped. The information was not anywhere in the textbooks.

“I don’t know,” I finally confessed.

“What kind of doctor are you?” he said.

I didn’t feel much better equipped when my wife had two miscarriages, or when our first child was born with part of his aorta missing, or when my daughter had a fall and dislocated her elbow, and I failed to recognize it, or when my wife tore a ligament in her wrist that I’d never heard of—her velluvial matrix, I think it was.

This is a deeper, more fundamental problem than we acknowledge. The truth is that the volume and complexity of the knowledge that we need to master has grown exponentially beyond our capacity as individuals. Worse, the fear is that the knowledge has grown beyond our capacity as a society. When we talk about the uncontrollable explosion in the costs of health care in America, for instance—about the reality that we in medicine are gradually bankrupting the country—we’re not talking about a problem rooted in economics. We’re talking about a problem rooted in scientific complexity.

Half a century ago, medicine was neither costly nor effective. Since then, however, science has combatted our ignorance. It has enumerated and identified, according to the international disease-classification system, more than 13,600 diagnoses—13,600 different ways our bodies can fail. And for each one we’ve discovered beneficial remedies—remedies that can reduce suffering, extend lives, and sometimes stop a disease altogether. But those remedies now include more than six thousand drugs and four thousand medical and surgical procedures. Our job in medicine is to make sure that all of this capability is deployed, town by town, in the right way at the right time, without harm or waste of resources, for every person alive. And we’re struggling. There is no industry in the world with 13,600 different service lines to deliver.

It should be no wonder that you have not mastered the understanding of them all. No one ever will. That’s why we as doctors and scientists have become ever more finely specialized. If I can’t handle 13,600 diagnoses, well, maybe there are fifty that I can handle—or just one that I might focus on in my research. The result, however, is that we find ourselves to be specialists, worried almost exclusively about our particular niche, and not the larger question of whether we as a group are making the whole system of care better for people. I think we were fooled by penicillin. When penicillin was discovered, in 1929, it suggested that treatment of disease could be simple—an injection that could miraculously cure a breathtaking range of infectious diseases. Maybe there’d be an injection for cancer and another one for heart disease. It made us believe that discovery was the only hard part. Execution would be easy.

But this could not be further from the truth. Diagnosis and treatment of most conditions require complex steps and considerations, and often multiple people and technologies. The result is that more than forty per cent of patients with common conditions like coronary artery disease, stroke, or asthma receive incomplete or inappropriate care in our communities. And the country is also struggling mightily with the costs. By the end of the decade, at the present rate of cost growth, the price of a family insurance plan will rise to $27,000. Health care will go from ten per cent to seventeen per cent of labor costs for business, and workers’ wages will have to fall. State budgets will have to double to maintain current health programs. And then there is the frightening federal debt we will face. By 2025, we will owe more money than our economy produces. One side says war spending is the problem, the other says it’s the economic bailout plan. But take both away and you’ve made almost no difference. Our deficit problem—far and away—is the soaring and seemingly unstoppable cost of health care.

We in medicine have watched all this mainly with bafflement, even indifference. This is just what good medicine is like, we’re tempted to say. But we’d be ignoring the evidence. For health care is not practiced the same way across the country. There is remarkable variability in the cost and quality of care. Two communities in the same state with the same levels of poverty and health can differ by more than fifty per cent in their Medicare costs. There is a bell curve for cost and quality, and it is frustrating—but also hopeful. For those getting the best results—the hospitals and doctors measured at the top of the curve for patient outcomes—are not the most expensive. They are sometimes among the least.

Like politics, all medicine is local. Medicine requires the successful function of systems—of people and of technologies. Among our most profound difficulties is making them work together. If I want to give my patients the best care possible, not only must I do a good job, but a whole collection of diverse components must somehow mesh effectively.

Having great components is not enough. We’ve been obsessed in medicine with having the best drugs, the best devices, the best specialists—but we’ve paid little attention to how to make them fit together well. Don Berwick, of the Institute for Healthcare Improvement, has noted how wrongheaded this is. “Anyone who understands systems will know immediately that optimizing parts is not a good route to system excellence,” he says. He gives the example of a famous thought experiment in which an attempt is made to build the world’s greatest car by assembling the world’s greatest car parts. We connect the engine of a Ferrari, the brakes of a Porsche, the suspension of a BMW, the body of a Volvo: “What we get, of course, is nothing close to a great car; we get a pile of very expensive junk.” Nonetheless, in medicine, that’s exactly what we have done.