The one thing all painters of fantasy and surrealism have in common is the belief that seeing with "the inner eye" of the imagination is more important than observing the world. Private fantasy is of major importance today in art. It began to take shape in the work of Goya in the nineteenth century. Today many artists' work is intensely personal in describing their own fantasies or imaginings.

Private art, by definition, is not public. An artist's way of telling us about his or her private world has to be personal and unique. How can he tell us about his own world of daydreams and nightmares? Why should he want to? How can what he has to say about it mean anything to us? Aren't our private worlds bound to be different from his?

The more we learn about the deep workings of the human mind, the clearer it becomes that we are all cut on the same mental pattern. Our imaginations and memories work much in the same way. They belong to the unconscious part of the mind; our experiences are stored there. We cannot control the unconscious part of us at will; but when we are lying in bed, or when we are thinking of nothing in particular, experiences come back to us and we seem to live through them again. They do not necessarily come back to us the way they actually happened; the unconscious likes to disguise them as dream images... in this form they can be lived with more easily.

We are always interested in learning about imaginary things, especially when the person who tells us about them knows how to make them seem real. A fairy tale put into the language of a daily newspaper would seem absurd. Told as an opera or ballet, it enchants us. This is just as true in painting. Look at "The Dream" by Henri Rousseau to see the magic of painting combining impossible or fantasy images.

"Mystery and Melancholy of a Street" by Giorgio de Chirico is similar in that it shows an imaginary world. In a deserted moonlit square with endless diminishing arcades, a child rolls her hoop towards a shadow in the distance. The scene is imaginary but this one is strangely sinister. The unknown is lying in wait.

If the De Chirico painting is troubled by hidden fears, then the work of Marc Chagall is enchanting and full of joy. In "I and the Village" the dreamlike memories of Russian folk stories and the Russian countryside are woven into a glowing vision. Chagall relives his childhood experiences which are so important to him and which shaped his imagination throughout his life.

During World War 1 the butchery and mechanised brutality was reflected in the art of the Dada movement. The artists involved in this were acting in protest. Their message was that all the usual values and beliefs of European society were meaningless and futile as they did not save humanity from a terrible war. The artist Marcel Duchamp was a major Dadaist. On the eve of World War 1 he painted "The Bride". This is a work of fantasy it shows a beautiful robot-like creature which has no soul, just beautiful engineering. Duchamp was mocking the hope that mankind was placing in technology.

Out of the Dada movement developed Surrealism. After the First World War artists tried to give their imaginations free rein and tried to let the instinctive, unconscious part of the mind take over. In the late eighteen century an English artist Alexander Cozens had tried to show his imaginary images by painting "blotscapes", and then adding missing details so that others could see them too. The Surrealists made similar use of chance effects and many of their pictures have the strange , irrational quality of dreams. Max Ernst was the most inventive member of the group. Ernst often combined collage with rubbings from pressed flowers and pieces of wood. He then completed images he found on the canvas, letting his imagination run riot.

Salvador Dali used Ernst's technique with great skill in the drawing, "Return of Ulysses", where he seized chance effects he had created and then turned them into an imaginary world. Dali's later paintings were very polished and he hides his techniques more thoroughly. A more typical painting by Dali and one which represents Surrealism very well is "Sleep" painted in oil on canvas in 1932. In this fantastic representation of sleep, only the head of the dreamer is seen, against a background of dream-like images. The delicate balancing of the figure indicates that, should a single crutch be removed, the dreamer will awake. This demonstrates the fragility of the state of sleep. Dali's meticulous attention to detail creates an atmosphere of enhanced hyper-reality.

As a member of the Surrealist movement he promoted the idea of absurdity and the role of the unconscious in his art.

Although he frequently provoked public outrage, Dali's reputation and contribution to art are undeniable. Having worked in Paris and New York, Dali returned to his native Spain in 1955, settling there with his long-term companion, Gala, of whom he painted many weird and wonderful pictures.

Réné Magritte (b. 1898, d.1967) was a Belgian artist who has become one of the other well known Surrealists. He often placed every day images in unusual or impossible settings which jarred the senses. He would give his paintings deliberately misleading titles. One of his most famous images is "The Treachery of Objects" which is a painting of a pipe, very precisely painted with the words, "Ceci n'est pas une pipe" written below it. Magritte appears to be contradicting reality by nonsensically naming something that does not need to be named, at the same time as denying that it is what it obviously is. By writing "This is not a pipe" beneath the picture of one, he illustrates that the image of an object must not be confused with the actual real and tangible object itself. The painting of the pipe questions the concepts of definition and representation. All is not as it appears to be, Magritte is saying, the picture thus represents a challenge to ordered society and an assault on the accepted way in which people see and think. Magritte's Surrealist paintings often use fantastic, disturbing and dream-like images, such as a steam train emerging from the centre of a fireplace, or a sky in which the clouds have turned into French loaves.