Empty Cup

It would be erroneous to consider the empty space in a drinking cup in opposition to the water that eventually fills it.  While true that the emptiness gets overcome and eliminated by the water that fills the cup, an empty drinking glass has not fulfilled its implied purpose.  Similarly, a full glass of water constitutes equal meaninglessness for its implied purpose remains unachieved.  Only by drinking the water and returning the cup to a state of void (*yin*) does the meaning of cup-and-water become realized.  Hence, an empty cup alone (*yin*) remains unrealized in its potential until filled (*yang*), which means that *yin* will be unfulfilled until overcome by *yang*.  At the same time, a full cup (*yang*) will remain unrealized in its potential until drank, thus returning to *yin*.

-- Dr. Steve Pearlman, author, instructor, and martial arts philosopher, The Book of Martial Power (2006) Chapter 69 "Yin and Yang" p. 210