When yin and yang meet, they will die. What does two plus two mean?

People are yang when they live, and yin when they die. When yin and yang meet, there is bound to be death, and yin and yang blend. People live as yang and die as yin. One day they met, but one of them was dead. They hug each other, but they can't touch each other. They can only look at each other with tears in their eyes.