 The distinction between li and qi provided a way to deal with the tension between the claim that the nature of human beings is good and the recognition that people need extensive self-cultivation in order to actually be good. Li is inherently good and is the same in all things. In that sense, we already have all that we need. The quality of qi, though, varies. Turbid qi—which manifests itself as selfishness and partiality—obscures li. Thus from the perspective of li human nature is good, but from the perspective of li and qi together, a person can be good, bad, or in between. On the psychological level, the work of self-cultivation is cultivating tranquility and impartiality; on the metaphysical level, one purifies qi so as to more perfectly express and participate in li.