 Because Yangism had largely faded into obscurity by the time that Sima Qian compiled his Shiji, the school was not included as one of the Hundred Schools of Thought.Yangism has been described as a form of psychological and ethical egoism.The Yangist philosophers believed in the importance of maintaining self-interest through "keeping one's nature intact, protecting one's uniqueness, and not letting the body be tied by other things."