“Thing” and “nothing” are metaphysical themes of thinking for major philosophers both in the West and in East Asia, such as Heidegger, Kant, and Laozi 老子. In light of a discussion of Heidegger’s understanding of thing-ing and no-thing and of his critical interpretation of Kant on the same issue, I shall in this essay reconstruct a Laozian theory of thing and nothing. My conclusion is that thing and nothing are not two “things,” as often assumed by an epistemological approach, but ontologically one thing cut by an absolute limit set up by human rationality which is contained either in our consciousness or in our languages.