Lao Tzu, an ancient Chinese thinker, Confucius' teacher, and the founder of Taoism in China, wrote "Tao Te Ching", which is regarded as a philosophical poem by later generations, though it is only about 5,000 words long. But every word bead gong, sentence is mysterious, extensive and profound, covering the world.

Laozi's philosophical thoughts have deeply influenced generations of Chinese children and exerted a profound influence on the development of Chinese culture and thoughts over the past two thousand years.

According to legend, more than two thousand five hundred years ago, at the age of fifty-six, he quit his official job and returned home. One day, he rode a green ox and went to the State of Qin to give lectures. Go to the Hanggu Pass (today's Henan Lingbao County), see the terrain is dangerous, mountains high, the city prestige, and the suspension bridge high vertical, can not pass. the original Hangu Guan Yin Xi, the night sky, see purple air, know that there will be a noble coming. Ask around, that is Lao Tzu abandoned the official westward tour, to pass through the hangu. Yin Xi has long Yangji Lao Tzu famous, know that he is kind, loving people, Tao Gao De Chong, deep knowledge, can know the Yin and Yang of heaven, people ask the fate. Yin Xi intends to leave Lao Tzu in Hanku Guan, so he ordered people to erect the suspension bridge, in order to find Lao Tzu. Lao Tzu can not see through, worried, the green cow good know master's mind, see this situation, two eyes a stare, tail a twist, four hooves suddenly born Ziyun. The host takes off into the air. Clouds surging under the ox, strewn with interlocking, from east to west, the longer and longer, all of a sudden over the Hangu Pass as if to build a purple bridge. In this way, Lao Tzu passed Hangu Pass.

When Yin Xi heard that Lao Tzu was flying over the city on a green ox, he was very surprised. He mounted a white horse and followed Lao Tzu closely. After twelve miles, I saw Lao Tzu riding a green ox slowly. Yin Xi urgent worship Lao Tzu, repeatedly begged Lao Tzu back to close. Lao Tzu was very kind and agreed to his request. Yin Xi showed great respect to Lao Tzu. He not only entertained him warmly, but also made the bed and folded the quilt. Lao Tzu wrote the Tao Te Ching of more than five thousand words in Hanggu Pass. After the manuscript was finished, he said goodbye to Yin Xi and left Hangu Pass by Qingniu. Continue westbound. This is the famous "Lao Tzu rode a green ox across Hangu" in history.