What is a dream?
For centuries, people have wondered about the strange places that they seem to visit in their sleep.   小题1: However, they have been valued as necessary to a person's health and happiness.
Historically people thought dreams contained messages from God. It was only in the twentieth century that people started to study dreams scientifically believing that they tell about a person's character. 小题2:  He believed that dreams allow a person to express fantasies or fears, which would be socially unacceptable in real life.
The second theory to become popular was Carl Jung's compensation theory. Jung, a former student of Freud, said that the purpose of a dream is not to hide something, but rather to communicate it to the dreamer.  小题3: Thus, people who think too highly of themselves may  dream about falling; those who think too little of themselves dream of being heroes.
Using more recent research, William Domhoff from the University of California found that  dreaming is a mental skill that needs time to develop in humans. , 小题4:  Until they reach age  five, they can not express very well what their dreams are about. Once people become adults,  there is little or no change in their dreams. The dreams of men and women differ. For instance,
The characters that appear in the dreams of men are often  other men, and often involve physical aggression.
The meaning of dreams continues to be difficult to understand.  小题5:  If you dream that a loved one is going to die, do not panic. The dream may have meaning, but it does not mean that your loved one is going to die.

A．Dreams make up for what is lacking in waking life.

B．However, people should not take their dreams as reality.

C．They have been considered as meaningless nighttime journeys.

D．It gives scientists chances to better understand human mind.

E．Children do not dream as much as adults.
F．They think their mind is trying to tell them something.
G．First, there was Sigmund Freud’s theory.