Do you have a good sense of humour? I think you must do if you’re enjoying this book!

Now, picture the grumpiest, strictest, unfunniest person you know — it might be a relative, a teacher, a character in a book you’ve read. Well, although it’s hard to believe, even they have humour. In fact, we all do.

Do you want to know why…?

Centuries ago, our bodily fluids were considered very important — so important in fact that they were thought to influence our every mood, such as grumpiness, happiness and sadness. And all those things sloshing around inside us were believed to keep us healthy, too. If your body had lots of ‘black bile’, for example (a horrible bitter substance), you would be sad. If it was yellow, you would be very irritable.

It all depended on the balance of these fluids — a bit like the ingredients in a cake. If the balance was more or less right, you would have calm and happy days.

These fluids, which included blood, were known as the ‘humours’. If you were ‘out of humour’, you would be very grumpy due to the lack of balance in your body. In ‘good humour’, however, meant that things were just right.

That’s why, over time, ‘humorous’ came to describe something funny.

By the way, sweets and fizzy drinks don’t count as bodily fluids, even if they do make you feel happy for a bit!