What is the difference between qi and essence?
Q: Taoist cultivation practices, herbal medicine and alchemy advocate the use of qi rather than essence. What is the difference between qi and essence? What is the meaning of refining essence and transforming it into qi?
Answer: This is an important question that should be clearly distinguished. It should be noted that essence and qi are originally from the same source. Essence is originally qi, and qi becomes essence. Here, qi refers to primordial qi. After primordial qi becomes essence, it is divided into two types: one is primordial essence, which is still qi at this point and has no form or shape. It does not have the turbid essence that comes later in life, and the alchemy classics refer to it as “clear water source”. If you collect it, you can form an elixir and attain enlightenment. The other is the turbid essence that comes after birth. At this point, the essence has already taken shape, becoming tangible and visible, and becoming the turbid substance that comes after birth. The alchemy classics call it the “source of turbid water”. If you harvest it, you cannot form an elixir. Even if you force it to become an elixir, it will be an illusory one that will surely go astray and be futile.
Some people who study Taoism do not know how to distinguish between the two and think that refining essence means refining semen. As a result, they try to pull semen back inside when they feel an erection, semen production, and the urge to ejaculate, and add what they call mental firepower in an attempt to refine it into true qi. They do not know that semen is a tangible object that is formed after birth, and no amount of firepower can turn it into qi. The Wuzhen chapter says, “You cannot use it when you see it, and you cannot see it when you use it.” This is the meaning. And after the semen is withdrawn, it can only temporarily return to the bladder and cannot enter the dantian. After a while, it will still be lost with urination, so what's the point? This is the fundamental difference between collecting semen and collecting qi.
The essence refined is the innate primordial essence, which does not need to be refined. The meaning of refining is to cultivate our primordial spirit in conjunction with the primordial energy, so that the spirit and energy become one, remain undisturbed, and are cultivated into a pill.
采炁与采精区别何在
问：道家修功，采药炼丹，主张用炁而非用精，请问采炁与采精有何区别？炼精化炁的含义何在？
答：这是一个重要的问题，应当辨析清楚。须知精与炁二者，本属一源。精本为炁，炁化成精。这里的炁指的是先天元炁，元炁化精之后，其精分为两种：一是先天元精，此时精尚为炁，无形无象，没有后天浊质，丹经谓之“清水源”，采之可以结丹证圣。一是后天浊精，此时精已成形，有形有象，成为后天浊质，丹经谓之“浊水源”，采之不可结丹，纵然勉强成丹，亦是幻丹，必会走失，徒劳无功。
有些学道之人，不知辨析于此，以为炼精就是炼精液，结果就在外肾勃起、精液产生、欲射未出之际，将其死拉活拽，硬扯回到里面，加以所谓意念火力，试图炼成真炁。不知此个精液，乃是后天有形之物，无论何等火力，也不可能炼成为炁。《悟真篇》云：“见之不可用，用之不可见。”即是此意。而且精液收回之后，只能暂时回到膀胱之内，不能进入丹田，时间稍长仍随小便而流失，何益之有哉！此即采精与采炁之根本区别处。
道家所云“炼精化炁”，所炼之精，乃为先天元精，先天元精，本不必化。炼化之意，是要把吾人元神，配合元炁而修养之，以使神炁合一，凝定不散，修炼成丹。