[originaltext] Dreams are expressions of thoughts, feelings and events that

Dreams are expressions of thoughts, feelings and events that pass through our mind while we are sleeping. Everybody dreams. But only some people remember their dreams. People have been trying to decide what dreams mean for thousands of years. Ancient Greeks and Romans believed dreams provided messages from the gods. Sometimes people who could understand dreams would help military leaders in battle. Some native American tribes and Mexican civilizations believed dreams were a different world we visit when we sleep.(20)In Europe, people believed that dreams were evil and could lead people to do bad things. 200 years ago, people awakened after four or five hours of sleep to think about their dreams or talk about them with other people. Then they returned to sleep for another four to five hours. Early in the 20th century, famous scientists developed different ideas about dreams. Austrian psychiatrist Sigmund Freud published a book called The Interpretation of Dreams in 1900. Freud believed people often dream about things they want but cannot have. For Freud, dreams were full of hidden meaning. He tried to understand dreams as a way to understand people and why they acted or thought in certain ways. Freud believed that every thought and every action started deep in our brains.(21)He thought dreams could be an important way to understand what is happening in our brains. Scientists believe it is important to keep researching dreams. Doctor Stickgold says it has been more than 100 years since Sigmund Freud published his important book about dreaming. Yet there’s still no agreement on exactly how the brain works when we are dreaming or why we dream.
20. What did Europeans think of dreams?
21. How did Freud interpret dreams according to the passage?
22. What does the passage mainly tell us?