The process for making a homunculus, as described in historical alchemical texts, is more of a symbolic and ritualistic procedure than a literal scientific one. The most famous "recipe" comes from the 16th-century alchemist and physician Paracelsus in his work De Natura Rerum.
It is important to understand that many scholars believe these instructions were intended to be an allegory for a spiritual process of self-creation and inner transformation, not a physical experiment. However, when read literally, the recipe is as follows:
The Paracelsus Recipe
1. The Vessel and Ingredients: Take human semen and place it in a glass vessel known as a cucurbit (a type of retort used in distillation). The vessel must be hermetically sealed, meaning it is completely airtight.
2. Incubation: The sealed vessel is then to be buried in a pile of fermenting horse manure (venter equinus in Latin) for a period of 40 days. The manure provides a consistent, gentle warmth that simulates the temperature of the human body.
3. Animation: After 40 days, Paracelsus claims that the contents of the vessel will begin to show signs of life, moving and stirring. At this point, it will appear as a transparent, miniature human form.
4. Nourishment: For the next 40 weeks (the length of a human gestation period), the alchemist must carefully nourish the homunculus. This is done by feeding it with the "arcanum of human blood," which is a highly debated phrase. It is thought to refer to a specially prepared blood essence or a concentrated form of spiritual energy.
5. Growth: Throughout this period, the vessel must be kept at a constant temperature. If all the steps are followed correctly, the transparent form will grow into a "true and living infant," with all the members of a human child, though it will be much smaller.
The Symbolic Meaning
While the literal instructions are strange and unscientific, scholars have interpreted them as a series of symbolic steps for the spiritual transformation of the alchemist:
Semen: Represents the fundamental creative force and the alchemist's own will or essence.
Sealed Vessel: Represents the purified and protected mind of the alchemist.
Horse Manure (Venter Equinus): Symbolizes a process of putrefaction and decay. In alchemy, this is a necessary step for spiritual death and rebirth. It is the "dark night of the soul" that must be endured before new, pure life can emerge.
40 Days/Weeks: These numbers are significant in many religions, representing periods of trial, purification, and transformation (e.g., Jesus's 40 days in the desert, the 40 years the Israelites wandered).
* "Arcanum of Human Blood": This is often interpreted as the alchemist's own spiritual essence or life force, indicating that the Great Work is an internal process that requires personal sacrifice.
In essence, making a homunculus was likely an allegorical description of the process of an alchemist achieving a higher state of consciousness, transforming their own base nature into something pure and perfected—a process similar to the turning of lead into gold.