"What really is the point of trying to teach anything to anybody?" This question seemed to provoke a murmur of sympathetic approval from up and down … - Douglas Adams

What I mean is that if you really want to understand something, the best way is to try and explain it to someone else. That forces you to sort it out in your own mind. And the more slow and dim-witted your pupil, the more you have to break things down into more and more simple ideas. And that’s really the essence of programming. By the time you’ve sorted out a complicated idea
into little steps that even a stupid machine can deal with, you’ve certainly learned something about it yourself. The teacher usually learns more than the pupil. Isn’t that true?

"Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space, listen..."

Far out in the uncharted backwaters of the unfashionable end of the Western spiral arm of the galaxy lies a small unregarded yellow sun. Orbiting this, at a distance of roughly ninety million miles is an utterly insignificant little blue-green planet, whose ape descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea. This planet has, or had, a problem, which was this. Most of the people living on it were unhappy for pretty much of the time. Many solutions were suggested for this problem, but most of these were largely concerned with the movements of small, green pieces of paper, which is odd, because on the whole, it wasn't the small, green pieces of paper which were unhappy. And so the problem remained, and lots of the people were mean, and most of them were miserable, even the ones with digital watches. Many were increasingly of the opinion that they'd all made a big mistake coming down from the trees in the first place, and some said that even the trees had been a bad move, and that no-one should ever have left the oceans. And then one day, nearly two thousand years after one man had been nailed to a tree for saying how great it would be to be nice to people for a change, a girl, sitting on her own in a small cafe in Rickmansworth suddenly realised what it was that had been going wrong all this time and she finally knew how the world could be made a good and happy place. This time it was right, it would work, and no-one would have to get nalied to anything. Sadly, however, before she could get to a phone to tell anyone, the Earth was unexpectedly demolished to make way for a new hyperspace bypass and so the idea was lost forever.

Why?' is always the most difficult question to answer. You know where you are when someone asks you 'What's the time?' or 'When was the battle of 1066?' or 'How do these seatbelts work that go tight when you slam the brakes on, Daddy?' The answers are easy and are, respectively, 'Seven-thirty in the evening,' 'Ten-fifteen in the morning,' and 'Don't ask stupid questions.