Gregory Petsko (CHEM) addressed the newest inductees of Phi Beta Kappa at the initiation ceremony Saturday in Spingold. Petsko, who is the Gyula and Katica Tauber Professor of Biochemistry and Molecular Pharmacodynamics, was asked to prepare this speech by faculty members of the Phi Beta Kappa Selection Committee.

First, let me congratulate all of you for having completed your college years with such distinction. Well done. Second, let me say that I’m deeply grateful to you for inviting me to talk to you today. But I think that you should also be grateful to me, because I’m going to be brief. You see, I know that the last thing a group of students want after years of formal instruction is to sit through another lecture. So I’m not going to give you one. But I would like to tell you a story.

It’s the story of a Frenchman named Joseph Meister. He was born in 1876 in a small village in the province of Alsace. In July of 1885, when he was nine years old, he was walking to school when he was attacked and bitten 14 times by a rabid dog.

In 1885, rabies was a death sentence, but Joseph Meister’s mother had heard that in Paris there was a man who thought he could cure rabies, although his treatment had never been tested on a human being. Two days later, Joseph Meister’s mother arrived with him at a small house at 45 Rue d’Ulm in Paris, and when the door was opened, she fell to her knees, begging the man who lived there to save her son.

The man, of course, was Louis Pasteur. He was not a physician—he was a rather famous chemist, in fact—but in those days the discipline you studied didn’t lock you into a career. And so, at 8 p.m. on July 6, 1885, Pasteur injected Joseph Meister with a preparation of a rabies-infected rabbit spinal cord that had been dried for 15 days. He repeated the procedure 12 more times over the next 10 days.

Joseph Meister did not develop rabies. And the people of Paris, who had lived for centuries in terror of being bitten by one of the rabid dogs that roamed the streets of the city, hailed Pasteur’s achievement as one of the great medical triumphs of the century.

Pasteur took a great risk in treating Joseph Meister with an experimental vaccine. Had Joseph Meister died, Pasteur’s dream of making medicine a science-based discipline might well have died with him.

There’s more to the story, and I’ll tell you the rest in a minute, but this first part illustrates one of the most important things I’ve learned from almost 40 years of being a scientist. I’ve learned that, if you’re afraid of making mistakes, you won’t get very far. In treating patients, of course, it’s desirable to be as perfect as possible, but in almost every other aspect of life you should learn to embrace error. Mistakes aren’t just a mechanism of learning—they’re the wellspring of creativity. Many of you have been conditioned, by parents and maybe also by teachers, to believe that mistakes are bad. Let me assure you that they’re not. If you’re afraid of making mistakes, if you take the comfortable route rather than risk error, you aren’t being brave enough, and you’re on the road to mediocrity. You see, from being a scientist, I’ve learned that excellence is the result of passion, preparation, persistence and imagination—but it also requires daring. Neglect any one of these things and you’ll end up average at best.

Let me share with you a few of the other things I’ve learned from being a scientist. I’ve learned that, if you think you know the answer, you will tend to get that answer, even if it’s the wrong answer. One of the hardest things I know of is to go through life with a mind that is open to all questions—and all answers—but it’s essential if you want to see things the way they really are. And a corollary of this point is to be careful never to confuse an assumption with a fact, because facts are what enable you to see reality, and assumptions are often the first step in being fooled.

From being a scientist, I’ve learned that you should examine everything. Not everything is what it seems to be, or what people tell you it is. I’m not saying you should be cynical. Cynics are sourpusses; nobody likes being around them, and they never get invited to the really good parties. What I am saying is that you should be skeptical. Always ask to see the data. And if somebody wants you to believe something and you aren’t given any evidence, be careful. A good way to figure out what you should do if you don’t have access to the data is to ask “Cui bono,” which is Latin for “Who profits?” Who is going to be rich or satisfied if I believe what they want me to believe or do what they want me to do? That will usually help you uncover the hidden agenda, and figure out whose side you’ll be on when the fog clears.

That fog, by the way, is usually created by those who claim to dispel it: the experts. From being a scientist, I’ve learned that one good experiment is worth 1,000 expert opinions. This carries over into all aspects of life: I haven’t met anyone yet who could predict the future with any consistent success, so if you base your opinions or your career choices—or your investments—on the advice of so-called experts, you’re asking for trouble. If you end up running a company and you pay any attention to what a bunch of analysts say, you are a damn fool. Dig out the facts, and think for yourself.

That applies right now, too, when you are debating what course your professional lives should take. Don’t pick a career or a field of research because other people say the brightest future is there—remember, no one can predict that with certainty. Find something you love, and be passionate, prepared, persistent, imaginative and daring. Following your passion won’t guarantee that you’ll be successful, but it’s the surest way I know of to a happy life. And happiness is underrated.

But you won’t be happy if you spend your time chasing what isn’t worth chasing. One of the most important things I’ve learned is that fame is a bubble that often pops; popularity largely arises by an accident; and money, as we all know, has a habit of flying away. Don’t make any of those the center of your life; that’s like trying to hold onto the wind. In my experience, the only thing that really endures is character.

Looking back on it, I think that probably the most important thing I’ve learned from being a scientist is not to get discouraged when you have setbacks, when things don’t work, when people criticize you, when that voice inside your head tells you that you’re not good enough. You see, in science it’s not how you start that matters; it’s how you finish. Most experiments don’t work the first time; many don’t work the fourth. You have to keep trying. If you’re doing something worthwhile, it doesn’t matter how many defeats you have, because the only battle you really have to win is the last one.

Now for the end of that story.

Louis Pasteur became the most famous and honored scientist of his generation. The French government built an institute in Paris so he could have the equipment and money to continue his research. The Institute Pasteur is still a great center of biomedical research: The virus that causes AIDS was isolated there in the 1980s. Louis Pasteur’s body lies beneath the Institute Pasteur in a spectacular vault covered in depictions of his accomplishments in Byzantine mosaics. I think you can say that he finished well.

There are lots of ways to finish well. Joseph Meister didn’t start that well, being a poor boy from a poor village who almost died horribly, but thanks to Pasteur he was given a chance to keep trying. He fought heroically with the French Army in World War I, and after the war he became a gatekeeper at the Institute Pasteur. On June 16, 1940, almost 55 years to the day after he made medical history, when the invading Nazi soldiers tried to force him to open the gate to Pasteur’s tomb, Joseph Meister took his World War I service revolver and shot himself, in a final gesture of gratitude to the man who had saved his life. So I think you would agree that he, too, finished well.

As I said, there are lots of ways to finish well. You don’t have to find a cure for a disease or end life with a grand gesture. All you have to do is remember that it’s OK to make mistakes, that you should strive to keep an open mind, that skepticism is a healthy thing, that character is more important than the trappings of success. And never forget that trend is not destiny; Defeat doesn’t have to be permanent. How you start is not what matters—it’s how you finish. This great university has given you a great start. My wish for all of you, is that you finish well.