In 481 B.C.（the 14th year of Aigong，Duke of the state of Lu），Confucius was in the state of Lu，revising The Book of Spring and Autumn.A man guarding the forest in the south of Qufu killed a stange animal，which was said to be a unicorn.Upon hearing this，Confucius said，"My doctrines is useless！" He stopped revising The Book of Spring and Autumn and gave up his work.