The Eight Trigrams

The eight trigrams are symbols designed to explain the creation of the Golden Elixir, Gold Pill or Pill of Immortality (金丹). The Eight Trigram Furnace is the furnace in which the pills are fired.

Supreme Lord Lao Zi was sitting in his elixir laboratory where immortal boys were using a plantain-leaf fan to fan the eight trigrams furnace where the pills of immortality were refined. -- Journey to the West, Chapter 39
Ancient immortals used the term Gold Elixir as a metaphor of the essence of true consciousness. -- Liu Yiming, The Inner teachings of Taoism

The eight trigrams can be arranged in two ways: precelestal (前天) or postclestial (后天). The precelestial is the unconditioned, celestial state, distinguished by oneness and true consciousness, when the Original Spirit is present, and the postcelestial is the conditioned, human state, distinguished by multiplicty and discriminating concsiousness, when the Original Spirit is hidden behind human activity suchs as acquired conditioning, compulsive habits, the six senses causing trouble, wandering thoughts and the seven emotions.

The trigrams Heaven ☰, Earth ☷, Fire ☲, and Water ☵ have multiple meanings. Understanding them is not simply a matter of gathering knowledge about them, but also requires that one sees their operation in oneself.

Qian and Kun are the door and the gate of change,
the father and the mother of all hexagrams.

-- Wei Boyang, 2nd c. Taoist master, Cantong Qi —Triplex unity

Qian and Kun, either as trigrams or hexagrams, stand for Heaven and Earth, yin and yang. The trigram Heaven is made up of three yang lines and is pure yang, while the trigram Earth is made up of three yin lines and is pure yin. The trigram Qian is in command of bestowal; the trigram Kun is in command of receiving nourishment. Change refers to the change and transformation of yin and yang. As yin and yang act upon each other they create the six trigrams Fire ☲, Water ☵, Thunder ☳, Lake ☱, Mountain ☶ and Wind ☴. Heaven and Earth are seen as Father and Mother, or Husband and Wife, while the other six trigrams are seen as Sons and Daughters.

The trigrams Heaven ☰ and Earth ☷ also symbolize the true breath.

Qian is firm and Kun is yielding, They are fitted to embrace each other, 
-- Wei Boyang, 2nd c. Taoist master, Cantong Qi —Triplex unity
There is a saying: As you breathe, so the firm and yielding rub against each other, so they form the very image of Qian and Kun , opening and closing. The method of inner development which produces a divine Immortal uses man's ability to 'reflect back his brightness to light up within. His outbreath and inbreath merge together into a stage of supreme peace.
 -- Yuyan, Commentary on the Cantong Qi

When the celestial (yang) is overcome by the mundane (yin), reality is obscured. This is like Heaven mixing with Earth; the yang in the middle of Heaven ☰ enters the palace of Earth ☷, so that the trigram of Earth is filled in and becomes Water ☵. When the mundane takes the position of the celestial, intellectual knowledge and emotions gradually develop. This is like Earth mixing with Heaven: the yin in the middle of Earth goes into the palace of Heaven, so the trigram of Heaven is emptied and becomes Fire ☲. Yin and yang are no longer pure and the true breath is lost. To return to pure yin and yang energy one needs to reverse this process in oneself. When one reverses the process, the trigrams Fire and Water are then seen as the medicine and Heaven and Earth as the crucible and furnace. They are the method or the tools to return to pure yang.

The gold crucible is something firm, strong, stable; this symbolizes single-minded concentration of will, by which one can bear the Tao. The jade furnace is something warm, flexible, even, peaceful; it symbolizes gradual progress of the work, by which one can persevere long and go far. The gold crucible is also called the crucible of Heaven; the jade furnace is also called the furnace of Earth. -- Liu Yiming, The Inner Teachings Of Taoism
The two hexagrams Heaven and Earth are taken for the crucible and furnace because the firmness of yang and the flexibility of yin are considered the substance. The two hexagrams Water and Fire are taken for the medicinal substances because the balance of firmness and flexibility is considered the function. -- Liu Yiming, The Inner teachings of Taoism

The crucible of Heaven represents single minded concentration of will to not allow the firing process to be interrupted, while the furnace of Earth represents the progress of the firing times.

Heaven and Earth set the stage,

Whilst Change travels in their midst.
Heaven and Earth take as images Qian and Kun.
Change is shown through Kan (Fire) and Li (Water):
Kan and Li are the functions of Qian and Kun.
Altogether streaming through the six empty spaces.
-- Wei Boyang, Cantong Qi

Fire can refer to the postcelestial fire of the human mind and to the precelestial fire of the mind of Tao. The fire of the human mind refers to the many desires and emotions that veil the Original Spirit. The pure consciousness of Heaven ☰ has been invaded by human emotions and conditioning, resulting in the trigram Fire ☲.

The restlessness of acquired energy in people is the yin fire; this is the false. The energy of harmony of essence and feeling in people is the yang fire; this is the real. -- Li Yiming,The taoist I Cing, hexagram #24, Return

The fire of the mind of Tao refers to the illumination of conscious awareness; the firing process that retrieves the presence of the Original Spirit and is seen as medicine.

In the same way water can be seen as the postcelestial water of human mind and the precelestial water of the mind of Tao.

True awareness is the product of Heaven, pure clear yang water, which is the elder water. Emotional desire is the product of earth, polluted yin water, which is the younger water.
-- Li Yiming, Commentary on Understanding Reality

Water of the human mind also refers to the emotional desires of the human mind. While fire of the human mind represents the strong energy of these emotions, water of the human mind refers to the endless stream of thoughts produces by these emotions. Elder water (the Water of Life) refers to the true awareness of the mind of Tao and is called true yang and is also seen as medicine and is represented by the trigram Water ☵.

Kan (Heaven) and Li (Earth) streaming through the six empty spaces refers to the medicine of yin and yang changing or moving through the hexagrams and trigrams. They take control, so to speak, over each of the other trigrams and create the changes — Thunder ☳, Lake ☱, Heaven ☰, Wind ☴, Mountain ☶, Earth ☷.

Wei Boyang uses the six trigrams to illustrate the `firing times' of the Elixir, but he also matches them with the six lines of the hexagram Qian. Why does he do this? Because the Elixir is the most precious treasure of the purest Yang, and Qian (Heaven) is the hexagram of the purest Yang. -- Yu Yan (The Secret of Everlasting life ,Commentary on the Cantong Qi)

In the Cantong Qi, Wei Boyang matches the six trigrams with the waxing and waning of the moon. Here the moon symbolizes the Furnace of Earth.

In the path of submission nothing is greater than earth; for a symbol of receptivity, nothing is more obvious than the moon. -- Liu Yiming, The taoist I Ching, Hexagram #2 Earth

To refine the elixir you must seek the crescent moon furnace.
-- Zhang Boduan, Understanding Reality

The crescent moon refers to the moon of the third day of the lunar calendar month, appearing as a hook of light in the direction of earth (southwest). That light curves upward, that is why it is called the crescent moon. What this crescent moon symbolizes in humans is a point of yang light shinning through the middle of extreme quiet. Among the trigrams it is Thunder . The point of yang light is nothing but the light of the mind of Tao. 
-- Liu Yiming (Commentary on Understanding Reality)

The trigram Thunder ☳ represents activity; the return of yang energy.

Zhen (Thunder) ☳ comes forth as an inkling,
And the Yang Breath makes it start:
Initial nine, withdrawn dragon.
-- Wei Boyang, Cantong Qi
Thunder ☳ is a dragon.
-- Li Yiming, Commentary on Understanding Reality
Thunder ☳ represents the celestial coming to the fore from beneath the earthly, celestial energy arising with time. When practitioners of the Tao activate the energy of will and go directly forward, this should be like the movement of thunder; only then can they rise up with firmness, and not be subject to compulsion by human desires.
-- The Taoist I Ching, Mixed Hexagrams #51 Thunder and #53 Mountain

The moon borrows the light of the sun. The waxing of the moon represents the yang light of the mind of Tao, which is conscious awareness, growing until it is full. There are six steps or phases. The six trigrams are matched with the six lines of the hexagram Heaven.

The holy man, who understands the mysteries of creation inherent in end and beginning, becomes superior to the limitations of the transitory. For him, the meaning of time is that in it, the stages of growth can unfold in a clear sequence. He is mindful at every moment and uses the six stages of growth as if they were six dragons (the image attributed to the individual lines) on which he mounts to heaven. -- (The I Ching p 371, Wilhelm/Baynes edition, Commentary on hexagram #1, the Creative)

The six firing phases are timed with one`s breath.

The true fire is one`s own spirit: the true times are one`s own breathing. Refining the medicine by means of fire in order to form the Elixir is like spirit driving breath in order to attest the Tao. -- Zhu Yuanyu 17th c. Taoist master (Commentary on the Cantong Qi)

Dragons can spit fire with each breath and are symbols of the firing phases.

Long ago, in an enchanted forge,
Sir Henry fashioned the Iron-Tree Dragons.
When a pure heart plays the magic bells,
The Dragons awake to fly in six directions.
The Dragon of the nether region will
flee from despair and bring hope.
The Dragon of Heaven will arrive
With the gift of true love,
And from the four corners of the earth,
Will come peace, health, wisdom and happiness.
-- The Dragon Tree Legend, Ron Baird

After one has refined the elixir and all mundane yin energy is burned away, one is pure and the work of doing is finished.

When the full moon of contemplation is reached, you will be pure.
-- Journey to the West Ch. 19
Spiritual alchemy must start with doing, restoring the primordial while in the midst of the temporal, recovering one's original jewel of life. At that point one embraces the fundamental and preserves unity, traveling the path of non-doing, thereby realizing the original essence of real emptiness. What can be done for all the quietists who only know non-doing and do not know doing? -- Liu Yiming (Understanding Reality)

The path of doing is called cultivating life (命). The path of non-doing is called cultivating essence (性).

The real people of ancient times said that essence and life should both be cultivated; so the work requires two stages. One of the paths of spiritual alchemy is cultivating life, one is cultivating essence. The path of cultivating life is the path of doing; the path of cultivating essence is the path of non-doing. The path of doing is prolonging life by certain arts; the path of non-doing is making the being whole by the Tao. -- Liu Yiming (Understanding Reality)

The path of doing uses inferior virtue. The path of non-doing uses superior virtue.

Superior virtue has no doing: there is nothing whereby it does. Inferior virtue does; there is something whereby it does. -- Daode Jing 38
Superior virtue performs the way of non-doing and thus fulfills essence (性). Inferior virtue performs the way of doing and thus fulfills life. (命)
-- Liu Yiming (Commentary on the cantong Qi)

Sun Wukong, The Monkey King from
Journey to the West, is jumping out of
the Eight Trigram Furnace
(click to enlarge)

The Postcelestial Eight Trigrams

Heaven, Earth, Fire and Water as
the four timeless hexagrams
(click to enlarge)

Buddha pointing to Heaven and Earth (Seiryouji Temple, Kyoto, Japan)

Pharaoh Tutankhamun (representing yang energy) shoots an arrow supported by his
wife Ankhesenamun (yin energy)
(click to enlarge)

Take the great bow of the sacred scriptures, place on it the arrow of devotion; then draw the bowstring of meditation and aim at the target, the Lord of Love. The mantra is the bow; the aspirant is the arrow, and the Lord the target. Now draw the bowstring of meditation, and hitting the target, be one with him. -- Upanishads (Hindu text)

Bodhisattva Guan yin, holding
the sun (Fire ☲) and the moon (Water )
(Click to enlarge)

Fudo Myo-o, the Unmovable King of Light, symbolizing the firm illumination of conscious awareness (9th C. AD Japan)

Hexagram #1 Heaven

The Chinese character 心 (xin) means "mind" and looks like the crescent moon.

Two dragons heads, one saying 'Ah' and one saying 'Om'. The dragon saying "ah' represents Thunder. (Kodaiji temple, Kyoto, Japan) Click to enlarge

The six trigrams of the firing times are also represented as dragons. Dragons can spit fire with each breath, which represent illumnation of conscious awareness of the firing times.
(Click to enlarge)

The Dragon of the Nether Region and the Dragon of Heaven chasing the Original Jewel of Life, symbolizing the Original Spirit.
(Click to enlarge)

Jizo Bodhisattva with the Jewel of Life, 13th c. Rokuharamitsuji temple, Kyoto, Japan,
by Unkei (Click to enlarge)

The ancient shape of
the Chinese character for virtue.