Childhood is about learning to walk – literally and metaphorically. We begin to explore the world and we begin to understand the world. One of the most important things we have to learn is the concept of death. Nothing lives for ever; all things must pass. But it’s better that children don’t meet this reality in its most disturbing and unpleasant forms.

That’s one reason that it’s good for children to have pets. They don’t just learn how to love and care for another living creature: they also learn that love and care aren’t enough to keep it alive for ever. A mouse or hamster can pass away in a couple of years. One day it can be bright-eyed and active; the next day it’s still and cold, having died quietly in its sleep. Cats and dogs have longer lives, but they too will grow old and pass away. By experiencing these smaller tragedies, children learn to face the fact of death and become better prepared for bigger tragedies involving not animals but people.

Grandparents grow old and pass away too. So, sometimes, do the young. Children can lose parents, siblings, friends and classmates to illness and accident. It can be very difficult for them to understand and accept what has happened. But it helps if they have experienced it before in a smaller and less serious way, by losing a pet and recognizing that all living things must pass away sooner or later.

Children may even have held funerals for their lost pets. Many of us can remember burying a goldfish or mouse in the garden: digging a miniature grave; using a shoebox for a coffin; saying a few words of farewell; covering the coffin with soil; marking the grave in some way; placing flowers there. To adults, it looks like a game, but it can be very serious to children. They’re learning how to act as adults, taking their first steps away from childhood. It’s a form of dressing-up or play-acting, so it is a kind of game, but games don’t have to be trivial or unimportant.

They teach us many things, but the consequences of getting it wrong aren’t as serious or harmful as they might be when it’s the real thing. In fact, making mistakes is a vital part of childhood too. And children can make mistakes about death, emotionally and psychologically speaking. Sometimes children grieve too much for a lost pet, refusing to accept that it is gone, feeling that the world is a cruel and uncaring place because something so important to them has not lived for ever.

That’s a mistake and it can be a useful lesson for a child to react like that. In time, they come to recognize that they were too emotional, that they didn’t accept the inevitability of death as they should have done. The world is imperfect. We can’t always get what we want and we can’t always keep what we have. Part of growing up is learning to face these facts and to keep our reactions to them within sensible limits. By keeping pets and seeing them pass away, children learn to do just that.