 A final reason why Zhu Xi’s ideas of li and qi ought to be taken as horizontal and not vertical complements, that is, as a complex unity and not as a metaphysical duality, is found when Zhu makes two seemingly contradictory claims about li and qi: (1) Li is prior to qi. 2) Li is not present apart from qi formations. Whereas 1) is usually regarded as a positive metaphysical claim, it means rather that li in this sense refers to “permanent possibilities of qi formation”. For example, for any particular qi formation to have come about, it had to have been possible for the qi constituents to combine in that particular way to yield those properties and  capacities.[24]  Whereas (2) is often taken to mean that li subsist until instantiated, it means rather that li are the patterning of real processes and things; they exist immanently in processes and things, though they can be analyzed and discussed separately from their real contexts. This is why, methodologically, Zhu insists that learners acquaint themselves with the li of things, processes, affairs, ethics, etc., by examining actual things, processes, phenomena, etc. He regards the study of li in abstraction from phenomena to be wooden, hollow, empty, etc. Hence, Zhu’s claims (1) and (2) and his methodological strategy all indicate that, for him, the relation of complementarity between li and qi is essentially horizontal.