Most people often dream at night. When they wake in the morning they say to themselves, “What a strange dream I had! I wonder what made me dream that.”

Sometimes dreams are frightening. Sometimes, in dreams, wishes come true. At other times we are troubled by strange dreams in which the world seems to have been turned upside-down and nothing makes sense.

In dreams we do things which we would never do when we're awake. We think and say things we would never think and say. Why are dreams so strange and unfamiliar? Where do dreams come from?

No one has produced a more satisfying answer than a man called Sigmund Freud. He said that dreams come from a part of one's mind which one can neither recognize nor control. He named this the “unconscious mind.”

Sigmund Freud was born about a hundred years ago. He lived most of his life in Vienna, Austria, but ended his days in London, soon after the beginning of the Second World War.

The new worlds Freud explored were inside man himself. For the unconscious mind is like a deep well, full of memories and feelings. These memories and feelings have been stored there from the moment of our birth. Our conscious mind has forgotten them. We do not suspect that they are there until some unhappy or unusual experience causes us to remember, or to dream dreams. Then suddenly we see the same thing and feel the same way we felt when we were little children.

This discovery of Freud's is very important if we wish to understand why people act as they do. For the unconscious forces inside us are at least as powerful as the conscious forces we know about. Sometimes we do things without knowing why. If we don't, the reasons may lie deep in our unconscious minds.

When Freud was a child he cared about the sufferings of others, so it isn't surprising that he became a doctor when he grew up. He learned all about the way in which the human body works. But he became more and more curious about the human mind. He went to Paris to study with a famous French doctor, Charcot.

At that time it seemed that no one knew very much about the mind. If a person went mad, or 'out of his mind', there was not much that could be done about it. People didn't understand at all what was happening to the madman. Had he been possessed（控制，掌握） by a devil or evil spirit? Was God punishing him for wrong-doing? Often such people were shut away from the ordinary people as if they had done some terrible crime.

This is still true today in many places. Doctors prefer to experiment on those parts of a man which they can see and examine. If you cut a man's head open you can see his brain. But you can't see his thoughts or ideas or dreams. In Freud's day few doctors were interested in these subjects. Freud wanted to know how our minds work. He learned a lot from Charcot.

He returned to Vienna in 1886 and began work as a doctor in nerve diseases. He got married and began to receive more and more patients at home. Most of the patients who came to see him were women. They were over-excited and anxious, sick in mind rather than in body. Medicine did not help them. Freud was full of sympathy（同情，慰问） but he could do little to make them better.

Then one day a friend, Dr Josef Breuer, came to see him. He told Freud about a girl he was looking after. The girl seemed to get better when she was allowed to talk about herself. She told Dr Breuer everything that came into her mind. And each time she talked to him she remembered more about her life as a little child.

Freud was excited when he heard this. He began to try to cure his patients in the same way. He asked about the events of their early childhood. He urged them to talk about their own experiences and relationships. He himself said very little.

Often, as he listened, his patients relived moments from their past life. They trembled（发抖） with anger and fear, hate and love. They acted as though Freud was their father or mother or lover.

The doctor did not make any attempt to stop them. He quietly accepted whatever they told him, the good things and the bad.

One young woman who came to him couldn't drink anything, although she was very thirsty. Something prevented her from drinking.

Freud discovered the reason for this. One day, as they were talking, the girl remembered having seen a dog drink from her nurse's glass. She hadn't told the nurse, whom she disliked. She had forgotten the whole experience. But suddenly this childhood memory returned to mind. When she had told it all to Dr Freud—the nurse, the dog, the glass of water —the girl was able to drink again.

Freud called this treatment the 'talking cure'. Later it was called psychoanalysis（精神分析） . When patients talked freely about the things that were troubling them they often felt better.

The things that patients told him sometimes gave Freud a shock. He discovered that the feelings of very young children are not so different from those of their parents. A small boy may love his mother so much that he wants to kill his father. At the same time he loves his father and is deeply ashamed of this wish. It is difficult to live with such mixed feelings, so they fade away into the unconscious（无意识的） mind and only return in troubled dreams.

It was hard to believe that people could become blind, or lose the power of speech, because of what had happened to them when they were children. Freud was attacked from all sides for what he discovered. But he also found firm friends. Many people believed that he had at last found a way to unlock the secrets of the human mind, and to help people who were very miserable. He had found the answer to many of life's great questions.

He became famous all over the world and taught others to use the talking cure. His influence on modern art, literature and science cannot be measured. People who wrote books and plays, people who painted pictures, people who worked in schools, hospitals and prisons; all these learned something from the great man who discovered a way into the unconscious mind.

Not all of Freud's ideas are accepted today. But others have followed where he led and have helped us to understand ourselves better. Because of him, and them, there is more hope today than there has ever been before for people who were once just called 'crazy'.