(excerpt)
修煉之道，不外神氣二者；調之養之，返乎元始之天而已。在先天，氣渾於無象，厚重常安；神寓於無形，虛靈難 狀。
The path of cultivation is none other than spirit and qi; harmonizing them, nourishing them, until the return to the primal Heaven.
While in pre-Heaven, qi is indistinct and formless, profound and weighty, constantly peaceful. Spirit resides in the shapeless, empty, lively and hard to describe.
一到後天，氣之重者而輕揚，神之靜者而躁動。氣不如先天之活潑，常氤氳而化醇；神不似先天之光明，脫根塵而獨耀。此命之所以不立，性之所以難修也。
But once in post-Heaven, the weightiness of qi becomes light and lifts, the quietude of spirit becomes disturbed and moves. The qi lacks the agility of the pre-Heaven; yin and yang mix into a rich complexity. The spirit lacks pre-Heaven’s clear brightness in which the contamination of the senses has been thrown off. This is the reason that Life cannot be set up and Essence cannot be refined.
學者欲得長生，須知氣必歸根。夫根何以歸哉？必以氣之輕浮者，複還於敦厚之域，屹然矗立，凝然一團，則氣還於命，而浩浩其天矣；以神之躁妄者，複歸於澄徹之鄉，了了常明，如如自在，則神還於性，而渾渾無極矣。
If those who study this desire a long life, they need to know that qi must return to its root. But how can it return to that root? It must be through taking the light floating qi and returning it once again to the realm of solid sincerity, standing majestically, congealing into a ball and then qi circles back into Life so that Heaven is vast and endless. Likewise, take the frenetic restlessness of the spirit and return it to the land of limpid clarity, knowing clearly with constant illumination, natural and all-of-itself. Then spirit comes back to Essence and undifferentiated infinity.
人奈何只見其小而不從其大耶？噫嘻痛矣！此言水輕而浮，為後天之氣，屬外藥；金沉而重，為先天之命，號真鉛——又號金丹，又號白虎初弦之氣，其名不一，是為內藥。先天金生水，為順行之常道，生人以之，故曰重為輕根。
Why do people only see the petty but do not comply with the great? This is referring to water that is light and floating being the qi of post-Heaven, which is the external medicine; and metal which is heavy and sinking being the pre-Heaven Life (also signified as True Lead, also signified as the Golden Elixir, or the qi of the first crescent of the White Tiger; the names will vary): this is the internal medicine.
In the pre-Heaven metal generates water, this being the normal course of the eternal Dao; humans are generated using this, and this is why Laozi says “Heaviness is the root of lightness.”
夫人生於後天，純是狂蕩輕浮之氣作事，以故水氣輕而浮，情欲多生，命寶喪失，所以易老而衰。君子有逆修之法，無非水複生金，輕返於重，以複乎天元一氣。是以終日行之，而不離乎輜重。不過亭亭矗矗，屹然特立，厚重不遷，養成浩氣，充塞乾坤而已矣。
Now humans are born in the post-Heaven, which is all crazed chaotic floating qi in operation, emotions and desires proliferate, precious Life is squandered, and thus one easily ages and dies.
The Junzi has a method of refinement by reversing this, which is basically water restoratively giving birth to metal. Lightness goes back into Heaviness, and returns to Heaven’s primal unified qi.
Hence one “travels all day without leaving the supply wagon.” There is only standing tall and upright, towering, majestic, capacious and unchanging, cultivating a noble spirit— which is to say, simply filling Qian and Kun.
此為逆修之仙道，煉丹以之。總之由有形以複無形，丹道之一事也。火燥而動，為後天之神，屬外藥；木靜而凝，為先天之元性，曰真汞，曰真精，又曰青龍、真一之氣，其名亦多，要皆內藥。先天木生火，為順行之常道，生人以之，故曰「靜為躁君」。
This Immortal’s Path of reverse cultivation is used in refining the elixir. But to summit up, “form” is returned to “formlessness”—a matter of the Dao of the elixir.
Fiery restlessness moves and becomes the spirit of post-Heaven: this is external medicine.
Wood quietens and congeals, becoming the primal essence of pre-Heaven (also called True Mercury, also called True Vitality, also called the Green Dragon, or the True Unified Qi; the names are various) and all of them are the internal medicine.
Pre-Heaven wood generates fire, the normal progression order of the Dao, by this means humans are given life, and so it is said: “Quietude is the Lord of Restlessness”.
The Fat Monk 