The ”virtue” referred in Five Elements by the ”internally-formed Virtue”, the ”externally-practiced virtue” and the ”non-internally-formed virtue” is actually a two-fold moral law. Such a virtue is exactly what Guo Dian-jian meant by ”internal Ren and external Yi” in other writings and also the key to the thoughts of Five Elements. The book emphasizes the doctrines about ”holiness” and ”wisdom,” showing the dualist inclination of moral practice; the first half k is about ”internally-formed virtue” and the ”externally-practiced virtue,” while the second half is about ”non-internally-formed virtue.” Five Elements had great influence on the later scholars like Mencius and Xun-Zi; regarding its thoughts and characteristics, it's more appropriate to ascribe the work to Zi-Si.