 Xing became a foundation for theories of motivation but its roots are in metaphysics. Xing derives from heaven and is closely connected to sheng 生, the term meaning to live or generate. Xing moves from the generic creativity or vitality of nature to the specific life processes of kinds of things. More concretely, xing was conceptualized as the dynamic flow of qi (vital energy). One recently discovered text from the late 4th century BCE (known as the Xing zi ming chu 性自命出) brings these levels together: 