The most sure sign of wisdom is a constant cheerfulness. Prospero is the wisest of all of Shakepeare's characters. The impact of cheerfulness is hard to define and easy to dismiss, even as we try to be happy.

A professor at the University of California, Berkeley decided to write a book about it. Cheerfulness is a theme in the works of great philosophers and writers from Shakespeare to Jane Austen, and how it is depicted in everything from 16th-century medical books to the Boy Scouts handbook.

It's a way of approaching actions and situations with cheer. I can say hello to you in a cheerful way. It is not part of the saying 'hello'.

Spinoza said it was anaffect. He says you can't have too much of it.

Cheerfulness is different from happiness due to the fact that you have some control over it. I can tell you to cheer up and that's what I want you to do. You can't be happy. You can't get it. There is nothing you can do about happiness.

He says that cheerfulness is not positive or hopeful. The thing is ephemeral. It keeps coming and going. A boost in one's emotional wellbeing raises one's energy levels briefly. It is hard to pin down because we don't really know what it is.

He says that it doesn't necessarily show on your face. I can tell if you are cheerful by the way you act.

It is accessible even in times of hardship. It was difficult for people who had suffered physical handicaps and been in accidents to get through the day. I realized that cheerfulness is a resource that can be managed and put into action. That seemed to me to be a precious and interesting thing that we don't think about a lot.

In order to find out if cheerfulness is an emotion people have thought about for hundreds of years and if the way we think about it has changed. The 16th century saw the emergence of cheerfulness as a modern phenomenon.

This is not optimism or positivity – it’s a resource of the self

The etymology of the word cheerfulness lies in an old French word that means face. Chaucer refers to it as a synonym for face. Madame de Stal, a French writer, said that if you put a cheerful expression on your face, it will spread to the inside of your body. The emotional energy coming from a person's face will transform the inside of them.

The idea that cheerfulness can spread from the outside to the inside is common in books and essays about cheerfulness, as is the idea that cheerfulness can spread from person to person. A flame is called cheerfulness by the philosopher Hume. He says that when a cheerful person enters a room where everyone is subdued, they swoop around the room and make everyone happy. The conversation became gay and lively. At a certain point, cheerfulness becomes something bigger than any of us and is related to our relationships to each other.

Shakespeare is interested in what happens when people lose their enthusiasm. One of the characters will say to another character that they have lost their cheer just before a terrible event happens.

This is what happens to Banquo before he dies. When tragedy strikes in Shakespeare's plays, it's when a character becomes isolated from their community.

The right way for a woman in the 19th century to deal with a crisis or a tragedy is to be cheerful. "She said little, but every sentence aimed at cheerfulness." Aiming at cheerfulness stops Marianne from getting sad and crazy. It is not about saying the sun will always come up tomorrow. It is about taking small steps at a time.

How do we want to be cheerful? Some good advice is provided by the American philosopher, according toHampton. No one can be a poet unless they are cheerful, because poets light the world with their light.

One way to be cheerful is to take delight in the world.

It is a deliberate decision for Shakespeare to look on all things well and for Montaigne to be cheerful.

Being able to rise above problems and insults is one of the qualities of cheerfulness. The slogan of Ragged Dick, a cheerful character in a 19th-century rags-to-riches novel, is: "That's a cheerin' thought." Someone will say to Ragged Dick that they are going to beat his brain in. Ragged Dick will say, 'Well, that's a good thought.' He has an ironic sense of humor and is able to ignore the situation.

It means focusing on the good and looking for the best in people

Writers show cheerfulness to be something anyone can put on, like a cloak. Charles Dickens tried to show how even the most wretched and miserable characters can cheer up when it's necessary. When disaster strikes at the heart of her community and little Emily is stolen by Steerforth, Mrs Gummidge is the only one who makes any remark other than a sigh.

Mrs Gummidge is a different person in a short time. Dickens wrote that she was a woman. She seemed to have lost the recollection of having had any misfortunes. She was cheerful.

The most melancholy member of the community suddenly becomes cheerful in a time of crisis.

That is one reason why he thinks we should be cheerful. There is a crisis in our own community. He says that cheerfulness is a tool we can use to deal with the instability of the world around us. Don't look at the evil in the world, but be Pollyanna-ish. You can use cheerfulness in the moment. We don't have a lot of resources, so we should use them.

Choosing to be cheerful doesn't mean walking on air with a therapist It means that you are committed to being a person who focuses on the good, looks for the best in people, and picks yourself up from bad events with determination to continue. It doesn't depend on good fortune. To walk through life with good humor, humility and optimism is a decision you make.

There is one last remedy if that is difficult. In medical books from the 16th to the 18th century, there was advice on stimulating cheerfulness. The cheering of the self will come from these things.

The book is available for £19.14 from