 Arguably the most well-known of Yang’s philosophical positions is his view of xing 性 (human nature/inborn characteristics), a view later criticized by Neo-Confucians in the Song Dynasty because of its inconsistency with Mengzi’s view, which had by that time become the “orthodox” Confucian position. Contrary to the earlier Confucian philosophers Mengzi and Xunzi, Yang held that human inborn characteristics contain both good and evil, and that moral development is a matter of cultivating the good aspects of it, while allowing the evil elements to wither. The fact that a particular characteristic is inborn or part of our nature, according to Yang, does not necessitate that we act according to it. Humans have the ability (through ritual and other tools) to shape our dispositions. Agreeing with earlier Confucians, Yang argues that what is contained in our nature must be developed in order to become either virtue or vice. The contents of our nature can be called good or evil, but an individual only becomes virtuous or vicious in connection with these characteristics once they are developed. The key passage in Fayan reads: