In Feng Shui, we do not deal with "dead" yin and yang. We are interested in how yin and yang intercourse 陰陽交媾 to generate life. It is inappropriate to try to create a rigid definition even when we compare two parts of a picture to see which part is yin and which part is yang. Rather, we can use models to help appreciate the concept.
The flower and the bee - which is yin, which is yang?
The bee is the one in action to make pollination a success. Therefore, the bee is yang while the flower is yin, right?
However, the flower sends out the message to attract the bee and is actually the one that initiates the action. The bee only responds to the message to come over. Therefore, the flower is yang while the bee is yin, right?
This is an example illustrating the teaching in
Qing Nang Jing:
Yang originates from yin. Yin breeds yang. Heaven follows form. Earth is attached to qi. This is what is known as the origin of transformation.
陽本陰 陰育陽 天依形 地附氣 此之謂化始 — 青囊經