What Is a Homunculus?

The recipe is one of the most quoted passages in the alchemical corpus, and it appears in Paracelsus’s De Natura Rerum (1537) and in several other texts of the Paracelsian tradition. Take a quantity of human sperm, seal it in a gourd-shaped flask (a cucurbit) with horse manure, leave it for forty days, or until it begins to live and move. The sperm will be transformed into a small, transparent being resembling a human being, but much smaller. Feed it with the arcanum of human blood. Keep it at a constant temperature. After due time, the homunculus will be a fully-formed human being, capable of all the arts and sciences, and able to confer great knowledge on its creator (Principe, The Secrets of Alchemy, 2013, pp. 110-115; Newman, Promethean Ambitions, 2004, pp. 230-245; Priesner, Geschichte der Alchemie, 2011). The recipe is one of the most famous and most controversial passages in the alchemical literature, and the controversy is itself part of the meaning.

What the recipe is doing

The Paracelsian recipe for producing a homunculus is not, of course, a literal recipe. No amount of sealed sperm, however long it is left in horse manure, will produce a small, transparent human being, and the Paracelsians knew this as well as anyone. The recipe is a literary device, a way of expressing a set of theoretical claims about the nature of life and the possibilities of the alchemical art. The recipe is also a provocation, a deliberate crossing of the line, and the crossing is part of the point. The alchemists had been writing about creating life in their flasks for centuries, but the Paracelsian homunculus recipe is the first to make the claim in quite this way, and the making is itself a piece of intellectual history.

The recipe is also a serious theoretical statement, and the seriousness is part of why the recipe has lasted. Paracelsus is making three claims about the nature of life:

That life is a separable principle. The life of the homunculus is derived from the human sperm, but it is separable from the sperm, and it can be developed independently. The claim is a theoretical commitment about the nature of biological life, and the commitment has implications for the alchemical theory of matter.
That the alchemist can manipulate life. The alchemist who can manipulate the tria prima can also manipulate the principle of life. The homunculus is the demonstration of the alchemist’s power over the living world, and the demonstration is part of the Paracelsian claim about the scope of the alchemical art.
That the creation of life is a sacred act. The alchemist who creates a homunculus is participating in the divine work of creation. The participation is part of the Paracelsian religious framework, and the framework makes the homunculus recipe a religious statement as well as a technical one.

The three claims are serious, and they have been influential in the development of the modern debate about the nature of life and the possibilities of artificial life. The homunculus recipe raises questions that are still being asked in the contemporary bioethics debate, and the questions are worth taking seriously.

The homunculus in the Faustian tradition

The homunculus is one of the most famous images of the Faustian tradition, and the homunculus appears in a long line of Faustian works from the late medieval period to the present. The most famous of the Faustian homunculus treatments is Goethe’s Faust, Part Two (1832), in which the homunculus is a major character.

In Goethe’s Faust, Part Two, the homunculus is produced by Wagner, Faust’s famulus, in a scene that is one of the most famous in the Faustian tradition. The homunculus is a small, transparent being who is able to speak and to think, but who is not yet a full human being. The homunculus travels with Faust and Mephistopheles through the classical underworld, where he encounters the figures of the Greek tradition, and the homunculus is finally dissolved in the embrace of Galatea, the sea-born beauty. The dissolution is a kind of success — the homunculus, lacking a body, finds one in the embrace of the sea-born goddess. The Homunculus scene is the most important alchemical literary text after Jonson’s Alchemist and is essential reading for anyone interested in the literary tradition (the cluster on alchemy in literature takes it up in more detail).

The homunculus in modern fiction

The homunculus has been a major figure in modern fiction, particularly in the science fiction and fantasy genres, and the modern treatments are worth taking seriously. The most famous of the modern homunculus treatments is Mary Shelley’s Frankenstein (1818), which is a major meditation on the homunculus theme. The creature of Frankenstein is the modern version of the homunculus, the artificial being produced by the application of scientific knowledge, and Shelley’s novel is one of the founding texts of modern science fiction. The connection to the Paracelsian recipe is not direct — Shelley’s creature is assembled from corpses, not generated from sperm — but the homunculus theme is the same theme, and the parallel is itself part of the literary tradition.

The homunculus theme has also been important in the modern fantasy tradition. J. K. Rowling’s Harry Potter series includes the homunculus as one of the magical creatures studied at Hogwarts, and the Fullmetal Alchemist manga and anime (2001-2010) treats homunculi as major characters. The homunculus has migrated from the alchemical laboratory to the contemporary novel, and the migration tells you something about the durability of the theme.

The homunculus in the modern ethical debate

The homunculus is, in the modern ethical debate, a powerful symbol of the possibilities and the dangers of creating artificial life, and the symbol has been more influential than is sometimes recognized. The modern biotechnologies — genetic engineering, cloning, synthetic biology — have made the creation of artificial life a real possibility, and the modern ethical debate has been informed by the long tradition of the alchemical homunculus. The CRISPR babies scandal of 2018, the He Jiankui case, was discussed in language that would have been recognizable to a Paracelsian, and the recognizability is part of the modern ethical inheritance.

The alchemical homunculus raises questions that are still being asked in the contemporary debate. What is the nature of life? Is life a separable principle, as Paracelsus’s recipe suggests, or a manipulable process, as modern biotechnology implies? What are the limits of the human aspiration to create? What are the responsibilities of the creator to the created being? The alchemical homunculus tradition informs the modern ethical framework for the creation of artificial life, and the framework is more useful than the popular treatments of “playing God” suggest.

The homunculus in the alchemical visual tradition

The homunculus is a major image in the alchemical visual tradition, and the image has been reproduced in a long line of alchemical treatises. The most famous of the visual treatments is the homunculus in the alchemical laboratory, often shown as a small, transparent being emerging from a flask or being held in the alchemist’s hand. The image is a powerful symbol of the alchemist’s power over the natural world, and the image is one of the more disturbing pieces of alchemical iconography. The homunculus has also been a major image in the modern art tradition, particularly in the work of the Surrealists and the Symbolists. The cluster on alchemy in art examines the visual tradition in detail.

The homunculus in the broader tradition

The homunculus is not a Paracelsian invention, although the Paracelsian recipe is the most famous. The Jewish golem tradition, the medieval accounts of artificial beings created by magic, and the ancient accounts of the construction of statues by Hephaestus and other gods are all part of the broader history of the artificial being. The Paracelsian recipe is a Christian, Latin, sixteenth-century entry in a much older tradition, and the older tradition is one of the reasons the Paracelsian recipe has been so durable. The recipe is one specific case of a universal human fascination with the creation of artificial life, and the fascination is not going away.

The significance

The homunculus is a powerful symbol of the human aspiration to create life, the human desire to transcend the limits of the human condition, and the human ambivalence about the powers of creation. The alchemists who described the homunculus were working through some of the most important questions of human life, and the questions are still being asked in the contemporary world. The homunculus is a living part of the contemporary cultural inheritance, and the alchemical tradition is one of the sources of the modern imagination.

The most useful reading of the homunculus, in my view, is the one that holds all three registers at once: the literal recipe that no one was ever going to follow, the literary device that says something serious about the nature of life, and the modern ethical symbol that asks questions we still cannot answer. The serious reader of the alchemical tradition should know that the homunculus recipe is not a literal procedure, and the reader should also know that the recipe is one of the more interesting pieces of alchemical intellectual history. The recipe is a piece of intellectual history, and the intellectual history is the most interesting thing about it.