The worst thing about television and radio is that they entertain us, saving us the trouble of entertaining ourselves. A hundred years ago, before all these devices were invented, if a person wanted to entertain himself with a song or a piece of music, he would have to do the singing himself or pick up a violin and play it. Now, all he has to do is turn on the radio or TV. As a result, singing and music have declined. Italians used to sing all the time. Now, they only do it in Hollywood movies, Indian movies are mostly a series of songs and dances trapped around silly stories. As a result, they don't do much singing in Indian villages anymore. Indeed, ever since radio first came to life, there has been a terrible decline in amateur (业余的) singing throughout the world. There are two reasons for this sad decline. One, human beings are astonishingly lazy. Put a lift in a building, and people would rather take it than climb even two flights of steps. Similarly, invent a machine that sings, and people would rather let the machine sing than sing themselves. The other reason is that people are easily embarrassed. When there is a famous, talented musician readily available by pushing a button, which amateur violinist or pianist would want to try to entertain family or friends by himself? These earnest reflections came to me recently when two CDs arrived in the mail. They are historic recordings of famous writers reading their own works. It was thrilling to hear the voices from a long dead past in the late 19th century. But today, reading out loud anything is no longer common. Today, we sing songs to our children until they are about two, we read simple books to them till they are about five, and once they have learnt to read themselves, we become deaf. We're alive only to the sound of the TV and the stereo (立体声音响). I count myself extremely lucky to have been born before TV became so common: I was about six before TV appeared. To keep us entertained my mother had to do a good deal of singing and tell us endless tales. It was the same in many other homes. People spoke a language they sang it, they recited it it was something they could feel. Professional actors' performance is extraordinarily revealing. But I still prefer my own reading, because it's mine. For the same reason, people find karaoke (卡拉OK) liberating. It is almost the only electronic thing that gives them back their own voice. Even if their voices are hopelessly out of tune, at least it is meaningful self-entertainment. The main idea of this passage is that ______.