Zang-fu in context of yin/yang and the Five Elements
Each zàng-fǔ organ has a
yin and a yang aspect, but overall, the zàng organs are considered to be yin, and the fǔ organs yang.
Since the concept of the zàng-fǔ was developed on the basis of
Wǔ Xíng philosophy, they're incorporated into a system of allocation to one of five elemental qualities (i.e., the Five Elements or Five Phases). The zàng-fǔ share their respective element's allocations (e.g., regarding colour, taste, season, emotion etc.) and interact with each other cyclically in the same way the Five Elements do: each zàng organ has one corresponding zàng organ that it enfeebles, and one that it reinforces.