《庚道集》Vol. 2

The second volume of Gengdao Ji records a method for refining an elixir called "Moon-Cinnamon Longevity Elixir." The process begins with preparing yellow sprout great elixir (four liang, crushed) as the foundational material, along with true mercury (one liang extracted from cinnabar) and a small amount of gold and silver filings.

The procedure unfolds as follows: First, seal the water-fire cauldron (a type of alchemical furnace) with six-one mud (a specially prepared clay). After drying the foundational material over heat, soak it in well water and place it in the furnace. Next, mix the true mercury with the gold and silver filings and pour the mixture over the foundational material. Then, assemble the water cauldron (cooling apparatus), seal the seams with paper strips, and apply an additional layer of six-one mud to ensure complete airtightness before drying thoroughly.

When setting up the alchemical workspace, refine the furnace structure using specialized clay. Begin by lining the furnace with purified paper ash for preheating, then place an iron tripod to stabilize the cauldron. Distribute four liang of charcoal evenly around the cauldron, maintaining proper spacing and height. Once the furnace temperature stabilizes, cover the coals with ash and add warm water to the water cauldron, monitoring regularly to prevent evaporation.

At mao hour (5–7 AM) and you hour (5–7 PM) daily, replenish the fire and water precisely. After half a month, open the furnace to add more mercury, reseal, and continue refining. Repeat this process four times until the combined weight of the foundational material and mercury reaches eight liang (at which point two additional liang of mercury may be added—an ancient technique called "four-plus-one"). Some practitioners advocate opening the furnace weekly, though incomplete mercury absorption may compromise efficacy.

Once the total weight exceeds ten liang, extend intervals to monthly or forty-nine-day cycles. When the foundational material surpasses one jin without further mercury additions, refine for three more months until it turns golden. Open the furnace, extract the material, and grind it to select fully solidified, mercury-free portions for consumption. The remainder may serve as "elixir mother" for cyclical reuse, embodying the "mother-child regeneration" principle of sustained refinement.

An appendix details mercury extraction from cinnabar: mix eight liang of cinnabar (five to seven liang also acceptable) with five liang of charcoal powder, adding honey (specific techniques unspecified). This method exemplifies the Daoist alchemical principle of "water-fire equilibrium" (shuihuo jiji), achieving material transformation through meticulous control of fire phases and timing.

This passage explains two crucial procedures in ancient Daoist alchemy: mercury extraction (chou gong) and the cultivation of yellow sprouts (yang huangya), referring to the initial formation of the elixir base.

The mercury extraction method requires first preparing an airtight alchemical furnace or ceramic vessel. After drying, mix cinnabar with charcoal powder using honey water, compacting the mixture firmly inside. Seal the furnace mouth with a clay disc and dry it, then drill five to seven small holes. Dig a pit in the ground to bury a large bottle filled 80% with water. Invert the cinnabar-filled furnace over this water bottle, ensuring perfect alignment, and completely seal the joint with Liu-Yi mud (a special sealing compound). Coat the surrounding area with coarse clay to prevent elemental conflicts between water and fire. Apply twenty catties of charcoal fire from the top, replenishing with ten to twenty more catties as needed, maintaining precise temperature control from dawn till dusk. After cooling overnight, opening the furnace reveals mercury transformed from cinnabar settled in the water bottle. High-quality cinnabar yields seven to eight qian of mercury per liang, while inferior grades produce only half. Residual stone dregs remain in the charcoal powder and can be washed out for examination.

For cultivating yellow sprouts, begin by mixing equal parts yellow earth and pine sand with paper fiber to make clay. Knead thoroughly, then seal and sun-dry the container. When placing the elixir base inside, add four qian of processed mercury for every two qian of base material before covering with the upper water vessel (shui ding). Seal the joint with the prepared clay, shaping the entire structure into a melon form with about three fen thickness of clay layer, then fire-dry. If the elixir base proves too hard, it must first be ground into fragments.

The fire-nurturing technique involves preparing a wide-mouthed small earthenware urn filled with paper ash or thatch ash burned for five to seven days. Place a short iron tripod inside to support the alchemical vessel steadily. The upper vessel must maintain water moisture. This process emphasizes the critical importance of fire regulation—a skill requiring oral transmission between master and disciple for proper mastery.

This passage details the specific preparation method for "Yellow Sprout Great Elixir" (Huangya Dadan) in Daoist alchemy, divided into two main sections:

The first part explains fire control during the alchemical process: Four-inch-long red charcoal pieces should be used, with firing commencing at mao hour (5-7 AM) and fuel replacement at you hour (5-7 PM). When adding charcoal, first cover the water cauldron (the alchemical vessel) with a tile, then use fire tongs to evenly distribute the ashes for consistent heating. Warm water must be added, with its temperature matching that inside the cauldron. Every seven days, open the cauldron to replenish mercury, though superior elixirs may require extending this interval to fortnightly or monthly.

The latter section reveals the secret of refining "Yellow Sprout Elixir Seed" (Huangya Dantou), an advanced medicine: The crucial principle lies in the harmonious interaction of water and fire (shui huo xiangji) and the balance of yin-yang. Adding mercury should resemble a mother nourishing her child—excessive amounts will neutralize the elixir's potency. During refinement, the medicine should be crushed to bean-sized particles, then roasted in the furnace until glowing red, with intense firing applied daily until mercury ceases to volatilize. Subsequently, wrap the elixir in boiled silk, simmer it in a sand jar with licorice water for one day, followed by another day with emblic fruit (Phyllanthus emblica). Finally, divide the medicine into small packets concealed within hollowed radishes for steaming until the radishes no longer darken—this marks successful completion.

The entire process emphasizes meticulous fire regulation and careful material handling, embodying Daoist alchemy's extreme attention to detail.

This passage documents several specific operational methods from ancient Daoist alchemy (Waidan), primarily concerning metal processing, elixir preparation, and material transformation techniques.

Regarding elixir preparation, medicinal ingredients are first ground into fine powder and calcined in a red-hot furnace. The resulting substance is then mixed with white porridge to form millet-sized pills for ingestion, which helps avoid side effects like vomiting and diarrhea.

The metal processing section details the "Gold Roasting Method": take one liang each of orpiment, realgar, sulfur, and sal ammoniac. Coat the interior of a large ceramic crucible (used in alchemical processes) with egg white, sprinkle ephedra powder inside, then add the four aforementioned ingredients. Heat with charcoal fire from all sides while gradually adding four liang of turmeric powder from toad bellies. After complete reaction, remove and grind the material before returning it to the crucible. Cover with another four liang of toad-belly turmeric powder, calcine under strong fire, then grind into extremely fine powder for use. In application, silver sheets are hammered thin, coated with saliva, dusted with the powder, and roasted with fierce fire—the color will immediately penetrate.

The "Guan Geng Method" records two techniques: The first uses Jiangxi green vitriol, alum, green salt, mint, and mercury boiled in a new iron pot until the mercury dries. The product is then wrapped and buried underground for a period until it hardens. The second method employs smithsonite (called "tuoti ya" in Uyghur), jujube pulp, wheat, and cypress leaves mixed with strong vinegar into a paste to encase treated mercury. After calcining in a bellows furnace for two shichen (approximately four hours), the substance is poured into pickling brine to obtain superior golden material.

Also documented is a method to give copperware a silver surface: grind salt gypsum (pre-boiled in crude nitre solution), love peas, and saltpeter into fine powder to polish copperware, with effects lasting half a year. Another technique mentions boiling sal ammoniac for half a shichen (about one hour) in iron-footed brake fern juice or water-field grass juice to deactivate it.

Finally mentioned is the "Liu Langxian's Qi-Responsive Great Elixir"—the name of an advanced elixir whose specific preparation method isn't detailed in this passage. These methods reflect ancient alchemists' explorations of material transformations, involving numerous specialized techniques and medicinal processing skills.

This passage describes the specific procedures for refining "sand" (a technical alchemical term referring to a certain mineral material) in ancient Daoist alchemy (Waidan). The entire process requires strict control of fire intensity and material ratios:

First, take one liang of "mother sand" (a foundational alchemical material) and mix it with five qian of "sand"—the more mother sand used, the better the effect. Prepare an iron tripod stand over a charcoal fire, heating from both top and bottom, with an iron cup (alchemical vessel) placed in the middle. Fill the iron cup two-thirds full with sesame oil, then add thirty croton seeds and a handful of Sichuan peppercorns. Place both the mother sand and regular sand into the oil and boil until the croton seeds turn scorched in color.

After removal, wrap the mixture in silk cloth with realgar (arsenic) inside, then squeeze out the oil and medicinal substances from the cup, shaping only the sand into pellets. Next, wrap these sand pellets with holly leaves, removing the veins and sealing them completely—this is called the "Laojun Ball" (referring to the deified Laozi). Prepare an outer layer using a mixture of rice vinegar, flour paste, and special clay (zini), then coat it with two or three layers of realgar solution to ensure no gaps remain. After thorough preparation, place it in the furnace and calcine with intense fire until glowing red. When the flames subside, remove it—the sand will have hardened.

Subsequently, melt five liang of salt in a crucible (gan guo), having previously dug a pit in the ground matching the crucible's size. When two-thirds of the salt has melted, quickly toss the sand into the molten salt, immediately covering it tightly with bricks and stamping it down to allow the reaction to proceed. After completion, remove and calcine again in the crucible. Prepare half a bowl of water with a paper channel in advance, then pour the sand into this channel to form the "treasure" (alchemical product). Finally, clarify it with a small amount of alum.

The text also records an alternative, simpler "Gan Geng" method: omitting the Laojun Ball preparation and instead using saliva to mix with smithsonite powder and lead carbonate as an outer coating for direct calcination. Another method involves burning five-direction grass and golden-straw ashes to extract their juices, then boiling them dry with molasses in a jar using husk fire to create a "reaction vessel" (kui, another alchemical term).

This entire process involves numerous hazardous chemicals (such as arsenic) and complex operations, representing typical ancient alchemical techniques in the pursuit of "transmuting base metals into gold"—modern readers are strongly cautioned against attempting such practices.

This passage documents the "Four Divine Vessel" refinement method in Daoist alchemy (Waidan). The principle "ten liang can nourish one liang" refers to using ten liang of materials to produce one liang of the elixir (Jindan).

The primary ingredients include: one liang each of cinnabar, sulfur, realgar, and orpiment - collectively called the "Four Divinities." These medicinal materials are first crushed to the size of rice grains, then tightly wrapped in layers of white silk cloth. Yellow-flowered nancao herb is pounded to extract its juice, which is then used to steam the wrapped materials over slow heat for seven days in a water bath, after which they are sun-dried.

Supplementary materials are then added: five qian of borax, five qian of chalcanthite, and one liang of sal ammoniac. These are steamed with warm water over slow heat for fourteen days before being sun-dried. Five liang of pure gold (chijin) is forged into a box, into which the prepared Four Divinities mixture is placed and sealed.

An outer casing is made with eight liang of silver formed into beads. Half the silver beads are placed at the bottom of an earthenware jar, followed by the golden box, then covered with the remaining silver beads. After sealing the jar, iron wires secure the positions of the golden and silver containers. The outermost layer is sealed with specially prepared salt-clay, which is dried before placing the vessel into an ash-filled heating container (huigang) for refinement.

Fire regulation requires precise control: For the first seven days, use one liang five qian of fire morning and evening; increase to two liang for the second seven days; two liang five qian for the third seven days; two liang seven qian half for the fourth seven days; and maintain three liang for the final three seven-day periods. The entire process spans forty-nine days. If the elixir appears black, continue heating until it turns yellow, indicating success.

Upon completion, each liang is divided into ten packets. For application, melt one liang of high-quality silver, adding three qian of the elixir in three separate additions. When the silver liquid surface becomes clear and impurity-free, it can be poured out to obtain the precious product. The scripture particularly emphasizes this method must remain secret, transmitted only to those who genuinely practice charity and virtuous deeds.

This passage meticulously records the ancient Daoist alchemical method for refining the "Four Divine Receptacles," primarily using four mineral medicines: sulfur, orpiment, realgar, and cinnabar.

First, select one jin (approx. 500g) of premium-quality sulfur, chiseled into pieces the size of lychee pits. Soak these in two dou (approx. 20 liters) each of motherwort juice and duckweed juice. Place the sulfur in a kudzu cloth bag suspended within the medicinal broth, boiling continuously for seven days and nights. After boiling, test a small portion—if it hasn’t fully achieved "subdued fire" (indicating proper medicinal refinement), continue boiling until qualified. Divide the processed sulfur into two portions, place them in large sweet pots (special crucibles), and smelt with thirty jin of hard charcoal under intense flame. Two people must rapidly fan the flames until the sulfur completely liquefies, then pour it into two Jianzhan (special ceramic cups). At this stage, the sulfur has transformed into a purified medicinal substrate.

Next, take four liang (approx. 150g) of raw sulfur, similarly processed into small pieces, and boil in herbal juice for one day and night. Use the previously refined one jin of sulfur as the "receptacle" (alchemical vessel), placing the four liang of sulfur like lotus seeds into a sandbox, separated by Kunlun paper (a specialized filter paper). Layer fine salt on top, followed by a stabilizing medicinal layer, and finally fill the vessel with White Tiger Powder (a specific mineral powder). Seal it and incubate in an ash pool with four liang of controlled heat for seven days, completing the sulfur refinement.

Then take four liang of leaf orpiment (a mineral), similarly processed into chunks and boiled in dock root juice for one day and night. Grind it into fine powder, mix with the previously refined four liang of sulfur, and combine with honey to form longan-sized pills. Place these in the sulfur receptacle for seven days of incubation. Next, take four liang of cockscomb realgar (another mineral), boiled in wild lettuce juice for one day and night, then mixed with the orpiment-sulfur pills to form new pills, similarly incubated for seven days.

The scripture states: "When one yellow dies, all yellows mourn; when one yellow lives, all yellows soar," meaning sulfur must be fully refined first before successively subduing orpiment and realgar. Finally, process four liang of mirror-surface cinnabar (premium crystalline cinnabar) by boiling in violet and knotweed juice for one day and night. Blend it with white aconite, borax powder, and honey, then incubate in the receptacle for seven days to complete the cinnabar refinement.

Through repeated boiling, mixing, and incubation, the four mineral medicines gradually fuse, ultimately forming the so-called "Divine Immortal’s Great Medicine." This exemplifies the extremely rigorous procedures and precise fire control in ancient alchemical medicine processing.

This passage describes the "Four Divine Crucible" refinement method from ancient Daoist alchemy, belonging to the practice of Waidan (external alchemy involving mineral-based elixirs and metal transmutation).

First, extract one jin (approx. 500g) of material from the sulfur crucible (a specialized alchemical vessel) for separate processing. Grind the previously prepared Four Divine Medicines (four esoteric herbal ingredients) into fine powder to create the crucible agent. Begin by combining three parts pure gold with seven parts mercury to form a sandy mixture, then boil it for one day with placenta (zǐ hé chē) and millet starch water. Wrap the processed sand in fine silk to form small longan-sized pellets. Initially stir-fry these in lime until hardened, then implant them like lotus seeds into the Four Divine Crucible, refining with four liang (approx. 150g) of controlled fire for seven days.

If results prove insufficient, extend the refinement for two additional days. After three to five such cycles, the crucible agent gradually becomes efficacious. At this stage, refine a 2:8 gold-mercury amalgam (gēng shā), continuing the cultivation process. When the substance turns hard with deep coloration and shows no loss during smelting, proceed to refine a 9:1 light amalgam (qīng shā). If this light amalgam achieves a gold-like golden hue, it confirms the crucible agent's spiritual potency, making it suitable for refining cinnabar (chén shā).

For creating gold-wrapped elixirs (hán tāi jīn), wrap each liang of cinnabar with gold foil, compact it, and refine for seven days as described. The resulting elixir retains its gold wrapping, radiating brilliant purple-gold luminosity.

To refine mercury elixirs, divide the Four Divine crucible powder into three portions. Place two portions in the vessel, create a small cavity, insert gold foil, then pour in mercury before covering with the remaining powder. Refine for seven days. Standard practice allows four liang of material per jin of crucible agent, though prolonged use diminishes efficacy; maintaining three liang preserves the agent's potency.

During the first year, this crucible agent requires seven-day fire refinement. After one year, the duration shortens to five or three days, and after three years, completion may require just one night. Through triennial accumulation, the crucible agent absorbs metallic essences, transforming into supreme purple-gold (zǐ mó zhēn jīn), which becomes applicable to other refinement processes.

The text concludes by noting the addition of sal ammoniac (náo shā) and borax (péng shā) for seven-day grinding refinement. After processing, each liang of mercury undergoes treatment in a water-polished dipper (a specific vessel). This meticulous record details alchemical ratios, operational sequences, and temporal controls, showcasing ancient Daoists' systematic exploration of metallic transmutation.

This passage documents the ancient Daoist alchemical technique of "gold transmutation," a secret method belonging to the tradition of Waidan (external alchemy). Here is the modern interpretation:

First, prepare one jin of sulfur, crushed into bean-sized pieces. Take the bark of the water-yielding tree (a specific plant), chop it finely, dry it in the sun, and boil it to produce five dou of concentrated liquid, which should then be clarified. Using a large porcelain urn, suspend the sulfur (wrapped in fine cloth) inside the vessel, securing it with a fine-mesh basket. Immerse the sulfur in the medicinal liquid and simmer over low heat for three "fu periods" (approximately 30 days), maintaining even heat throughout. After boiling, remove the sulfur and sun-dry it, dividing it into eight portions for later use.

Simultaneously, prepare eight specially treated crucibles: smoke-treat fifty-liang-weight gan pots (alchemical vessels) by burning water-yielding tree bark. Melt two liang of pure gold into liquid form, then quickly pour it into the smoke-treated crucible, immediately adding two liang of the processed sulfur. Cover the pot mouth promptly with a tile to prevent gas leakage. Repeat this process eight times, then break open the cooled crucible to retrieve the product.

The text emphasizes that this is a superior elixir formula transmitted by Master Pu (a renowned Daoist alchemist), passed down through the lineage from Ge Kejiu to Chen Shuzi. Though the method appears simple, it possesses the power to harness the creative forces of heaven and earth. Therefore, it is stipulated that the technique may only be transmitted to three individuals within seven hundred years. Those who obtain this method may attain the status of national preceptor, but must use it solely for benefiting humanity—strictly prohibiting misuse or casual disclosure.

The latter section describes the "method of dead yin-yang": take one liang of yin-yellow and four liang of yang-yellow, combining them with six medicinal herbs including sanguisorba and euphorbia to brew a concentrated decoction. Suspend the yin and yang yellows in a sand pot, simmering them in the medicinal liquid over low heat for fifteen fu periods (about 150 days), continuously replenishing the liquid to maintain moisture. The gold produced through this method may only be used for external medicinal compounds, never as a vessel for Neidan (internal alchemy) practice.

This passage describes the ancient Daoist alchemical method of refining "Red Gold" (Chigeng), belonging to the practical techniques of Waidan (external alchemy) metallurgy. Here is a modern interpretation of the step-by-step process:

Preparation of "Dead Sal Ammoniac": Regardless of quantity, sal ammoniac (ammonium chloride) is pounded with arrowhead weed or Marsilea quadrifolia to extract natural juice. After boiling and calcination, it loses its reactivity, making the treated sal ammoniac more effective.

Core steps for refining Red Gold: Take five taels of red gold (likely referring to cinnabar or a metallic compound) to make a reaction vessel, adding "Two Yellows" (orpiment and realgar). Mix in five qian of the treated sal ammoniac. Construct a larger outer vessel, placing a sulfur-containing container at its center surrounded by packed sulfur. Seal the vessel's mouth with red halloysite mixed with vinegar, then apply a two-finger-width layer of Liu-Yi Mud (a special Daoist sealing compound). After drying in shade, place it in an ash pool.

Fire control: Use "Mao-You fire" (alternating gentle and strong flames) to refine for one hundred days. After completion, grind the Two Yellows into powder—one qian of this powder can transmute one tael of mercury into superior Red Gold.

Mercury transmutation specifics: Place one tael of mercury in a gan pot (alchemical vessel), sprinkle one qian of the refined Two Yellows powder over it, cover with a small amount of transparent rosin, and add three to five drops of sesame oil. Seal the pot mouth tightly with a tile shard, then heat with surrounding charcoal fire. When the pot glows red and the sound ceases, pour out the contents to obtain superior Red Gold. If the color appears overly red, blend with silver for adjustment.

Advanced refinement: Cast six taels of successfully transmuted Sacred Gold into a new reaction chamber. Add two taels each of the Two Yellows and imported sulfur, then mix the Sacred Gold flakes with the medicinal powder for further refinement. Alternatively, use five taels of refined Two Yellows to transmute Sacred Gold into a new reaction vessel, layering it as base and cover for continued sulfur refinement—the resulting product can transmute mercury into Red Gold.

These methods form an interlocking cycle where repeated refinement and transmutation purportedly achieve infinite metallic transformations. It should be noted that these alchemical records contain numerous technical terms and symbolic expressions, while the actual operations involve high-temperature chemical reactions with considerable danger.

This passage documents several methods used by ancient Daoist practitioners to refine elixirs, primarily involving purification and transformation processes of minerals such as arsenic trioxide and mercuric chloride.

The first method involves calcining a mixture of placenta powder (zǐ hé chē) and arsenic trioxide. Specifically, one liang of arsenic powder is thoroughly mixed with one and a half liang of placenta powder, then placed in a gan pot (alchemical vessel). The mixture is first heated with a gentle flame that is gradually intensified. The resulting medicinal base is considered most suitable for cultivating mercuric chloride, with reportedly superior efficacy compared to other formulas.

The second method describes sublimating mercuric chloride: Mercury, salt, alum, and saltpeter are ground into fine powder and mixed together, then sealed inside a specially designed alchemical cauldron. A small opening (called the Mysterious Pass or xuán guān yī qiào) must be left at the top to allow steam to escape. Only after the steam completely dissipates is the vessel fully sealed. Finally, processed "dead arsenic" is used to catalyze transformation, said to produce miraculous effects.

The third presents a more complex mercuric chloride refinement process: First, boiling water is used to remove impurities from the mercuric chloride, which is then wrapped in multiple layers. The outer wrapping consists of a mixture of medicinal herbs like langdu and soap pod combined with honey, while the outermost layer requires a paste made from pounding camphor willow root and garlic together. The entire package is placed in a special container and calcined with charcoal fire. Controlling the fire intensity is particularly crucial here—the practitioner must observe changes in the ash color to adjust the heat. Successfully refined elixirs were believed to enable "bone transformation" (referring to transcendent physical metamorphosis).

Finally, a rapid arsenic calcination method is recorded: Arsenic trioxide, mercury, and sal ammoniac are mixed in specific proportions, ground together, and sealed in a special clay pot. This is then calcined in a specially designed furnace using charcoal fire.

These methods collectively demonstrate the strict requirements ancient alchemy placed on fire control, material ratios, and sealing techniques. Terms like "Mysterious Pass" reflect unique concepts in Daoist alchemical tradition. Modern readers should note these methods involve highly toxic substances and must never be attempted.

This passage records several specific operational methods of Daoist alchemical practices, primarily concerning the refinement processes of minerals like orpiment and realgar, as well as the production method of "Yellow Sprouts" (a technical alchemical term referring to the substance formed by the reaction of lead and mercury).

Regarding the method for subduing orpiment: First boil it with chicken-gut herb juice for a full day and night, then dry it in shade. Next, spread herbal powder beneath it in a container and calcine with ten jin of fire. After cooling, remove it. Each qian (an ancient unit of weight) can be used to transform cinnabar silver with excellent results.

The detailed procedure for making Yellow Sprouts: Take five or three liang of lead essence, melt it into a cake shape, and place it in an earthenware jar. Add three liang of mercury, keeping it about two inches above the lead cake. Seal the container with Six-One mud (a specialized alchemical sealing material) and cover it with a water bottle. Use three liang of gentle fire to nurture it for seven days. Upon opening, the mercury will have adhered to the lead cake, forming needle-like golden crystals called the "First Transformation." Repeat this process of adding mercury and nurturing with fire seven times over forty-nine days to ultimately obtain "Purple-Yellow Sprouts."

During the refinement process, about twelve liang of product can be obtained from the lead block, with approximately three liang of residual mercury remaining at the bottom. Additionally, about three liang of reddish substance will condense on the container lid, called "Solitary Cinnabar." These products can be steamed with cow's milk, ground into powder, and mixed with jujube pulp to form pills. Taking three pills daily on an empty stomach with wine can greatly supplement primordial Qi (Yuanqi), calm the spirit (Shen), stabilize the corporeal soul (Po), and expel pathogenic influences, showing remarkable effects in treating various illnesses.

These alchemical products exhibit different color transformations within the crucible and are called the "Mother of Reverted Elixir," their efficacy being too profound to fully describe. It should be noted that the alchemical methods recorded involve heavy metals and pose actual operational dangers—modern practitioners must never attempt to replicate them.