This paper is about the epistemological significance Wang-Bih's doctrine of Yi, pointing out that Wang's commentary of Yi was only a rendition of the style of Zhou Yi , with neither creativity in methodology nor any imposition of his own values of Neo-Taoism.  His commentary of Yi shared merely a few philosophical features with his Neo-Taoism in making people and circumstances the themes of trigrams and taking Confucian principles as the foundation of his commentary.  Theoretically, the sixty-four trigrams of Zhou Yi were assumed to be the situations of people's changes rather than a scheme of cosmology.  Most contemporary scholars assume that Wang-Bih's commentary of Yi applied Lao Zi's doctrine to Zhou Yi.  Such an opinion is the subject of this paper, where we claim: the doctrine of Yi was the source of both Confucianism and Lao Zi's doctrine; it is fair to say that the text of Zhou Yi was further developed in Lao Zi's doctrine rather than Wang-Bih imposing the latter on his commentary of Zhou Yi . As for Wang's ontological thinking in his interpretaion of Lao Zi's doctrine, it was actually an ontological question about abstract speculation, not directly relevant to Wang's methodology of interpreting the doctrine of Yi.  Wang-Bih was addressing the style of Zhou Yi, while contemporary scholars are confused in the fundamental question of philosophy.  Wang-Bish's commentary of Lao Zi was indeed about an ontological question, while the style of Zhou Yi was another question of commentary that doesn't have to be confused with the ontological thinking in Wang's commentary of Lao Zi.