I am trying to remember why I was attracted to science as a child. Was it because I liked to ask 'why'? Of course, every young child asks why a hundred times a day. Curiosity is central to being alive. Babies are curious. Dogs and cats are curious too. Animals and humans, we all want to look into boxes and under stones, to find out what's there.

It is enough even to hear a door creak open, for us to speculate whether it is our mother or brother that is coming in. Clearly we feel a fundamental need to have an explanation, what scientists call a 'theory', for everything.

Why is this? Almost three thousand years ago the Greek philosopher Socrates replied to this question by saying that "an unexamined life is not worth living". Our experience of life is made up of a confusion of sensations coming from our surroundings; the sun, the wind, the trees .. So long as we are alive we seek stories linking these disconnected experiences into a pattern.

The stories that we scientists tell are only one of many sorts, such as poems, plays and novels. Scientific stories make surprising and persuasive links between sun, wind and trees. The sun's heat causes the wind to blow, the wind and sun together energize the trees through the chemical factory in their green leaves. An amazing story.

Like all good stories this one has shape; it is, in fact, circular. As you know, animals (you and I among them) breathe the oxygen that is emitted by the trees, and then return to the air the chemical, called carbon dioxide, needed by the trees. So nature nourishes the trees, the trees nourish us, and we help feed the trees - round and round forever, provided we don't interfere too much with the working of nature, for if we do both we and the trees will suffer.

Is that what scientists are; storytellers? People who make patterns out of experiences that otherwise would have no discernible shape?

That is largely what we are, but it leaves out some things that you also know to be true about science. Science is fun, science is precise, and science is powerful.

Why is science fun? Why, in fact, do I do it? Well, to start with there is something magical about its powers; something that makes scientists, the best of whom are children at heart, able to do extraordinary things.

I remember getting a letter, shortly after I won the Chemistry Nobel prize, from a group of Swedish schoolchildren. "Dear professor", it read, "Warmest congratulations on the prize. We are studying chemistry. Would you please come and blow up our school." To these kids I had become a magician, able to dispel boredom by launching their school into the sky.

What, then, is the magic of science? The obvious answer is that scientists theorize about things that can be 'quantified', things to which numbers can be attached. So, in describing you, we would be less likely to say that you are handsome or plain and more likely to say that you are 150 cm tall and weigh 45 kilos.

You can see why the kids in the Swedish school wanted me to blow the place up. I mean, that is a pretty boring way of describing a human being.

The reason that it is such a useful description is that you can tell some stories with numbers that you cannot tell with words. By a logical process called arithmetic I can tell you the most likely height and weight of all the students at your school. But there is no way that I can tell you their most probable appearance. Numbers restrict what you can say, but improve the precision with which you can say it.

If Albert Einstein in his most famous discovery had simply said that something we call 'mass' (how heavy things are) is related to something called 'energy' (a general name for motion), he would have made a poetic statement. When, however, he explained in a mathematical equation what tiny mass produces what vast amount of energy, he said something that could be tested by others. It turned out to be so true that scientists soon built on his work to develop ways of converting controlled amounts of mass into energy. This changed the world.

First it produced a terrible new way of blowing things up, called a 'nuclear bomb', because it converted the mass of the nucleus of an atom into energy for use in weapons. This was an evil application of science (we'll get back to that). At the same time Einstein's equation opened the way to unlimited amounts of energy for doing mankind's every day work, since it will be possible to convert a few drops of water from the ocean into huge amounts of energy. (This will be a 'fusion reactor' - people have yet to make such a device work properly, but they will).

What about the important question of controlling science? I said that science seems to some people like magic. Well, sometimes magicians, in stories at any rate, start things they cannot stop. Are scientists like that? Not really.

Science teaches us about nature; why the moon seems to get bigger and smaller, why the inhabitants of countries at the bottom of the earth (such as Australia) don't fall off, why nobody is ten metres tall, and a lot more.

Unlike dogs or cats, we ask such questions and are able to find answers for them. The answers are so true that they lead us on to even greater discoveries, such as the link between energy and mass. Not only is there no harm in this new understanding, as Socrates said it makes our lives have meaning. We see patterns where previously we saw confusion. Life takes on new beauty.

When we talk about science getting out of control, we are really talking about what you and I do with the new understanding that scientists give us. Do we for example use the new discovery that mass can be converted into energy, in order to destroy people as if they were some kind of pest? Or do we use the same discovery to make people's lives easier, by keeping them warm and healthy?

This is a decision that is made not by the scientists, but by everybody. It is a decision made by society, of which the scientists form a part. For, as a scientist, you are also a citizen. Increasingly, scientists are playing their part as citizens who, because of their special knowledge, can be influential in shaping a more decent world.

It simply is not true that because we discover some powerful magic we are forced to use it for evil purposes. The choice is ours. We can equally well use new science for good.

Scientists have something special to offer in building a better world. They have, for hundreds of years, regarded the discovery of truth as being more important than who discovers it. That doesn't mean that they are uncompetitive. They compete with each other like crazy. They want to be the one to win a Nobel prize. This makes it all the more remarkable that they share their knowledge world-wide, that they help each other whatever their religion or nationality, and that they trust one another not to tell lies. The reason they do this is because, though they value their own personal success, they value the success of science even more.

An international community with links of trust around the world, is a wonderful and precious thing. It can be a powerful force for good. All scientists are pleased to be part of this global brotherhood and sisterhood. I have used my own links with scientists at home and abroad all my life in order to work for peace, and respect for human beings.

Meanwhile I have had a life in which I have been paid to play. I haven't been paid much, but my toys continue to be the best. My newest allows me to tickle molecules with the light beam from a laser, and then to see the molecules react, one at a time, to form new molecules.

I must admit that this is an infuriating toy, because most days it doesn't work at all. That is worrying since I have to make new discoveries if I am to be allowed to continue doing science, which is what I love to do.

So you can imagine the delight when finally that wretched machine for looking at molecules works, and I and my students get a glimpse of something nobody has ever seen before. We share for a moment in the relief and wonder that Christopher Columbus must have felt when, just at the moment that all seemed to be lost, a smudge of land appeared on the horizon. At that moment we are united with all the discoverers of history, and are proud to call ourselves scientists.

But how, you may ask, does one succeed in science? Above all, I would say, by wishing to do so. People of many different talents have succeeded in science, but nobody has succeeded who did not passionately want to do so.

If, perhaps, you are worried that by the time today's scientists leave the scene and your turn comes there will be nothing left to discover, stop worrying. What we know is surely only a tiny fraction of what remains to be known. At the centre of the atom, in the nucleus of the living cell and at the outer edges of the universe lie new worlds awaiting their discoverer.

Could that be you?

To view original German article on the Süddeutsche Zeitung Web site see: http://szARCHiv.diz-muenchen.de/REGIS_A11871903;internal&action=hili.action&Parameter=polanyi