Xun Zi 荀子 (Master Xun) is a Confucian text of the late Warring States period (310-210BCE). It is not rated as a classic because it contains unorthodox philosophical ideas. It is mostly a Confucian text but on certain points it is more Daoist or legalist. Xun Qing wrote that man was inherently evil, which differed from Mencius and later Confucian scholars. For example: he held that through ritual and education man became good.
“Xunzi was one of the three great Confucian philosophers; the other two were Confucius and Mencius. Many who have studied Xunzi are convinced that he was one of the greatest thinkers who ever lived.” (From Knoblock's translation)