How do you give someone confidence? Teachers think about this a lot. So do governments: the financial news at the moment is all about confidence.
Confidence is a priceless thing; monstrous sums of money cannot buy it. But the strangest thing about the economic crisis is not the mind-warping sums of money involved. It is something teachers know all about: the relationship between confidence and reality.
Confidence is not always appropriate, of course. If you are going for a walk where there are lions, confidence is not going to help you. Yet the weird thing about losing confidence is that it can create lions where there weren't any.
Most teachers have seen pupils fail just because they thought they would. Likewise, loss of confidence recently wiped Pounds 2.7 trillion off the world's markets.
If the world woke up on Tuesday thinking that it was only worth 12p, it would only be worth 12p. A young Martian could then buy the world with its pocket money and still have change for Jupiter.
It is the most startling example of a numerical value system gone mad that I have ever seen.
Then I remembered the league tables, and the exam results, and the yearly drone about falling standards and loss of confidence in the system.
We all teach under a heavy burden of proving our own worth, and that of our pupils, in numerical terms. The league tables are the stock exchange of education. OK, we are unlikely to wake up to find 2.7 trillion marks wiped off our A-level results. But the annual moan that exams are not as tough as they used to be does corrode confidence in the job we do.
At the same time, when pupils get their results and bounce with joy, their confidence is given a boost, one that will stay with them despite the wails from the national press.
What's more, the surge in confidence that pupils get cannot be measured in numbers or recorded on the system, and is therefore safe from its vagaries.
Clearly, confidence is a spookily powerful thing. But what is it?
Confidence isn't a feeling; it's a belief. The word comes from Latin confidere, "to have complete trust in". Similarly, the word "credit" comes from credere, "to believe". Making people confident is not just about making them feel better. It's about managing what they believe - about themselves and about the world they are stepping into.
This process is often hilariously badly presented in lazy films about teaching. You know, the kind where the teacher keeps saying to the class: "You just gotta believe in yourself! You gotta have confidence!"
Er, no, it's the teacher's job to make that happen. Telling someone that they should just have confidence is like saying: "You just gotta speak French!"
Boosting confidence is a subtle and delicate process. You have to coax people to take risks without scaring them. You have to encourage their efforts without lying to them.
How do you even start?
Being a teacher is about editing the reality confronting your pupils. A very important part of this is not telling them too much.
Those who are not teachers sometimes think that teaching is mostly about explaining things. To do this, surely you just tip up everything you know all over people? If they look unhappy, you do it again. Eventually they will get it.
Well, no, they won't. You have told them too much. The cloud of facts you have dumped on them is like a swarm of locusts in their mental sky. They have lost confidence because the locusts have formed the words "You can't do this" in their heads.
A good teacher knows when to shut up. And how to say something simple enough to restore the child's faith that the world is not a trap.
By contrast, a non-teacher will just keep talking, which sends confidence down further. The mind is having to process too much, just when it is already anxious and unable to see what is important.
This is part of the problem facing the world's financial systems: there is too much gloomy information flying around. To make the world a less threatening place, you first have to make it smaller.
A teacher confronted with a miserably confused class can say: "Right, close your books and look at this." But governments cannot tell everyone to stop reading scary newspapers. If you cannot edit reality down to a more friendly size, it is very hard to create confidence. Money won't do it. You can lead a bank to money, but you can't make it lend.
Making people believe that it is all right for them to take another step forward in an uncertain world - that is what it is to create confidence. It's not easy, but it's one of the most amazing things that a teacher, or a government, can do.
Catherine Paver, Writer and part-time English teacher.