For example, yin deficiency can also be thought of as cold deficiency. With a lack of cold in the body, false heat signs can be seen. For example, yin deficiency will also have a minor deficiency of yang that puts it just below its balanced level. Summer will eventually turn to winter, day will become night, even the most wild sugar rush will eventually lead to a resounding depression. The change is not spontaneous but needs certain factors or precursors to exist.
Internal factors are primary, yet external factors also have an effect.
In addition, the timing of these things must be right. Consider the transformation of matter to energy.