heshang gong provides what kohn calls the "first evidence for taoist meditation" and "proposes a concentrative focus on the breath for harmonization with the dao." eduard erkes says the purpose of the heshang gong commentary was not only to explicate the "daodejing", but chiefly to enable "the reader to make practical use of the book and in teaching him to use it as a guide to meditation and to a life becoming a taoist skilled in meditative training."