"In China Taoism is one of the "three teachings" (along with Buddhism and Confucianism). It took shape only gradually, during a slow gestation that was actually a progressive integration of various ancient lines of thought. No precise date can be set for its birth, and the integration of outside elements into the religion has never ceased. If we add to this the enrichment of Taoism throughout its history with new revelations and new inspirations, we can see how open a religion it is, constantly progressing and evolving, and how difficult it is not only to date its first appearance but also to define its boundaries. Thus we can legitimately say, along with Livia Kohn, that "Taoism has never been a unified religion, and has constantly consisted of a combination of teachings based on a variety of original revelations." Thus it can be grasped only in its concrete manifestations, and it is meaningless to speak of Taoism as a whole. As I put this work together, however, I came to realize that if there is a single thread that runs through Taoism, it lies in its genealogy and in the cumulative and integrative process of its evolution."