Do you ever automatically say 'God bless you' when someone sneezes? Did you ever cross your fingers when making a wish? Most people who do these things never think about why they do them. They just do them. But there is a reason. Both acts are meant to insure good luck. They are little superstitions that have come down to us from an earlier time, when everybody believed in good and evil spirits. And even in our modern world, when men are traveling to the moon, we are still practicing some of these ancient habits in our daily lives. In ancient times, men believed that the soul lived in the head. Every time someone sneezed, he was risking the danger of dislodging that soul and blowing it out the nose into the outside world. So, as insurance against a lost soul, people would say 'God bless you' to be sure that God would catch the soul and return it to its rightful owner. Some people today toss a bit of salt over their left shoulder if they happen to spill any at the dinner table. This practice once had a serious purpose. In an earlier time, men believed that evil spirits always stood on their left side and good spirits on the right. So any time they spilled some of the precious stuff, they would throw a bit of it over their left shoulder to keep away the evil spirits. Since the evil spirits stood on the left, and the good spirits on the right, the right side was considered the lucky side of the body. Putting your best foot forward meant starting out on the lucky side, with your right foot first. That was a guarantee of good luck at whatever you were about to do. We still speak of ' putting your best foot forward,' although we don t always start walking with the right foot. The main idea of the passage is that______.