元宵节为什么要张灯结彩？

大家都知道元宵节要点花灯，张灯结彩、点响炮竹，放烟火，课大家知道为什么元宵节要点灯吗？这里有一个关于元宵节点灯的传说
there are many different beliefs about the origin of the lantern festival. but one thing for sure is that it had something to do with religious worship.
one legend tells us that it was a time to worship taiyi, the god of heaven in ancient times. the belief was that the god of heaven controlled the destiny of the human world. he had sixteen dragons at his beck and call and he decided when to inflict drought, storms, famine or pestilence（瘟疫）upon human beings. beginning with qinshihuang, the first emperor to unite the country, all subsequent emperors ordered splendid ceremonies each year. the emperor would ask taiyi to bring favorable weather and good health to him and his people. emperor wudi of the han dynasty directed special attention to this event. in 104 bc, he proclaimed it one of the most important celebrations and the ceremony would last throughout the night.

another legend associates the lantern festival with taoism. tianguan is the taoist god responsible for good fortune. his birthday falls on the 15th day of the first lunar month. it is said that tianguan likes all types of entertainment. so followers prepare various kinds of activities during which they pray for good fortune.
the third story about the origin of the festival is like this. buddhism first entered china during the reign of emperor mingdi of the eastern han dynasty. that was in the first century. however, it did not exert any great influence among the chinese people. one day, emperor mingdi had a dream about a gold man in his palace. at the very moment when he was about to ask the mysterious figure who he was, the gold man suddenly rose to the sky and disappeared in the west. the next day, emperor mingdi sent a scholar to india on a pilgrimage（朝圣）to locate buddhist scriptures. after journeying thousands of miles, the scholar finally returned with the scriptures. emperor mingdi ordered that a temple be built to house a statue of buddha and serve as a repository for the scriptures. followers believe that the power of buddha can dispel darkness. so emperor mingdi ordered his subjects to display lighted lanterns during what was to become the lantern festival.

关于灯的传说
传说在很久以前，凶禽猛兽很多，四处伤害人和牲畜，人们就组织起来去打它们，有一只神鸟困为迷路而降落人间，却意外的被不知情的猎人给射死了。天帝知道后十分震怒，立即传旨，下令让天兵于正月十五日到人间放火，把人间的人畜财产通通烧死。天帝的女儿心地善良，不忍心看百姓无辜受难，就冒着生命的危险，偷偷驾着祥云来到人间，把这个消息告诉了人们。众人听说了这个消息，有如头上响了一个焦雷。吓得不知如何是好，过了好久，才有个老人家想出个法子，他说：“在正月十四、十五、十六日这三天，每户人家都在家里张灯结彩、点响爆竹、燃放烟火。这样一来，天帝就会以为人们都被烧死了”。
大家听了都点头称是，便分头准备去了。到了正月十五这天晚上，天帝往下一看，发觉人间一片红光，响声震天，连续三个夜晚都是如此，以为是大火燃烧的火焰，以中大快。人们就这样保住了自己的生命及财产。为了纪念这次成功，从此每到正月十五，家家户户都悬挂灯笼，放烟火来纪念这个日子。