The sky is vast and the universe is infinite; Joy begets sorrow and knowledge is empty. Looking at Chang 'an in the sun, the martial arts will meet in the clouds. The terrain is deep in the South Pole, high in Tianzhu and far from Beichen. It's difficult to climb mountains and mountains. Who feels sorry for the lost people? Meet by chance, full of foreign guests. When I miss the emperor, what year was I in the mysterious room? Preface to Wang Teng Pavilion