What is the original quote of “To be calm is the highest achievement of the self"?
To be calm is the highest achievement of the self.---Yogi Bhajan.


Note that based on Wikipedia 


  'Yogi Bhajan was born on August 26, 1929 into a Sikh family in Kot Harkarn, Gujranwala district, in the province of Punjab (now in Pakistan)'.


Firstly, he is not Chinese, also he don't speak Chinese, the original text certainly not in Chinese.