On the Cause for the Style change in His Latter Deriod Doems of Wan Anshi

In the latter period of his life,wan Anshi took mo untain and river and Buddism as the major conteut for his poems, His style also changed into elegant and accurate, but still peaceful and broad minded, For his style change,besides in his latter period of life, he was forced to retreat from the position of the prime Minister, gettingaway from the power stryggle center, thus his mood naturally tended to be calm ;and also Wan was born open-minded,he took one's social position and reputotion among officials as nofhing;also during this time he devoged himself into studyimg Buddism and followimg its principle,could be the main reasons