Homunculus

The homunculus ("little man") is an alchemical claim rather than a folk creature, and it has a datable text. The treatise De Natura Rerum, circulated under the name of Paracelsus (early sixteenth century), gives a recipe: human seed sealed in a vessel and putrefied in horse dung for forty days until something transparent and man-shaped stirs, then nourished daily with human blood and kept at the warmth of a mare's womb for forty weeks, whereupon a living, tiny, well-formed child is said to result, which will teach its maker every art.

The idea sits within a wider early-modern debate about generation, and it is often linked to preformationism, the theory that a fully formed miniature organism is already present in the seed or egg, which some illustrators drew as a tiny man in the sperm. As a figure the homunculus passed into literature, most famously in Goethe's Faust, Part Two, where the alchemist Wagner produces a luminous spirit-child in a flask, and into twentieth-century psychology, where C. G. Jung read the alchemists' talk of making an artificial man as a symbolic account of inner transformation rather than a laboratory procedure.

The instructions are explicit and often quoted. Human seed is sealed in a vessel and left to putrefy in horse dung for forty days, at which point something begins to move and take shape; it is then fed daily with human blood and kept at the same warmth for forty weeks, after which a small living person is present, fully formed but transparent, and can be raised as a child. The passage appears in De Natura Rerum, printed under the name of Paracelsus after his death.

What it means is contested and has been for a long time. One reading takes it literally as a generation experiment, in a period that accepted spontaneous generation and had no reason to think this impossible in principle. A second reads it as alchemical allegory, in which the vessel, the putrefaction and the forty days are the standard stages of the work described in biological language. A third reads it as a claim about art surpassing nature, made deliberately to provoke.

Two later confusions are worth separating out. The homunculus that Wagner makes in the second part of Goethe's Faust is a literary creation working from this material, not a report of it. And the tiny curled figure drawn inside a sperm cell in Nicolaas Hartsoeker's optical treatise of 1694 belongs to a different debate, about preformation in embryology, and was offered as a hypothesis rather than an observation.