Have you ever found your mind a million miles away while someone was making a speech at a meeting You probably felt sorry and made up your mind to pay attention and never have daydreaming again. Most of us, from earliest school days, have been told that daydreaming is a waste of time. Early experts in psychology paid no attention to the importance of daydreams or even considered them harmful. At one time daydreaming was thought to be a cause of some mental illness. They did not have a better understanding of daydreams until the late 1980s. Eric Klinger, a professor of psychology, said, "Daydreaming is one of the main ways that we organize our lives, learn from our experience, and plan for our futures ... Daydreams really are a window on the things we fear and the things we long for in life." Daydreams are usually very simple and direct, quite unlike sleep dreams, which may be hard to understand, it’s easier to gain a deep understanding of your life by paying close attention to your daydreams than by examining your sleep dreams carefully. Daydreams help you recognize the difficult situations on your life and find out a possible way of handling them. Daydreams cannot be predicted; they move off in unexpected directions which may be creative and full of useful ideas. For many famous artists and scientists, daydreams are a main source of creative energy. Daydreaming used to be considered ______.

A. very simple and direct
B. unimportant or even harmful
C. a necessary part of thinking
D. none of the above