Former heaven essence is like a patrimony or trust fund we inherent at birth. Latter heaven essence is like money which we save in the bank. It is that part of our daily economy above and beyond our operating expenses. When we store it as acquired jing essence, it and our former heaven essence together become our body's capital. It is said in alchemy that it takes gold to make gold and that the more gold one has, the more one can make. When applied to our inner alchemy, our original gold is our jing essence, both former and latter heaven. When these two essences are full and abundant, organ function is strong, metabolism is efficient, and we generate a profit each day. Therefore, it takes jing to make jing and the more jing we have, the more we can make. When we age, however, instead of living on our interest, we run a negative daily balance and are forced to dip into our capital. Eventually we consume all our capital and we go bankrupt or die.
Essence, Qi, Spirit
It is said in Chinese that jing essence (material basis) becomes qi (functional activity) and when qi accumulates it becomes shen or spirit. Shen means consciousness and mental/emotional activities. Excessive thinking or excessive emotionality consume great stores of qi and, therefore, jing essence. That is why the fourth basic foundation of good health is a healthy mental attitude. What is meant by a good attitude in Chinese medicine is spelled out fairly exactly. When the seven emotions -- joy, anger, grief, worry, fear, fright, and melancholy -- are appropriate to their stimuli, these are natural subjective experiences and their experience is the purpose of life. Nonetheless, their experience does consume jing essence. Jing essence without shen or mental activity is meaningless in human terms just as a candle which doesn't shed light is also useless. The consumption of jing essence through our conscious experience is what is called in Chinese our shen ming. Ming means brilliance or light. Jing essence's purpose is to be transformed into the light of consciousness.
It is further said in Chinese that shen should apprehend emptiness and that this apprehension should also be reduced to nothingness. This gets a little abstruse but is worth everyone's understanding, patient and practitioner alike. The apprehension of emptiness means that, through one's life experiences, one understands that nothing, whether internally experienced or externally existant, is permanent or real. If one feels any experience all the way to its depth, it becomes empty. All experiences are reductable to an essential emptiness. Not only are they fleeting but they are of a single, unexpressable, indescribable taste. No matter whether one experiences joy or anger, fear or sadness, these mental/emotional experiences are evansecent and in no way alter or affect the innate nature of the shen spirit.
When one understands that the shen is inviolable, essentially unharmable, and indestructable, one's experience, whether of good or bad, becomes like a movie projected on a screen. The movie is not the screen and no matter what drama is ennacted on the screen, the screen is not harmed or affected. If one can apprehend this, then, in Chinese, one can say that spirit apprehends the essential emptiness of experience. However, if one then becomes attached to this concept of emptiness, that itself can cause an obstruction to the free flow of reality. Therefore, it is further said that emptiness must also be understood as nothingness or no-thing-ness. When one does, this is the absolute good mental attitude which is ultmately healthy.