Rebis, from the Latin res bina meaning "two-thing" or "double thing," denotes the paradoxical substance in which two opposing principles have been reunited into a single, stable entity. In alchemical iconography, the Rebis is most commonly depicted as a hermaphrodite, a figure possessing both male and female characteristics simultaneously, representing the union of Sulphur and Mercury, Sol and Luna, the fixed and the volatile, the hot-dry and the cold-moist. The Rebis is not merely a mixture of opposites but a genuine synthesis, a new substance in which the contraries have been so thoroughly integrated that they can no longer be separated.

The concept has roots in the earliest alchemical traditions. Zosimos of Panopolis described philosophical mercury as "the hermaphrodite, who is eternal, who is attracted by its own elements," identifying the dual-natured substance with the universal agent of transformation. De Jong traces the hermaphrodite motif through medieval alchemical manuscripts, noting its appearance in the Buch der Heiligen Dreifaltigkeit (1420), the Aurora Consurgens, and the Rosarium Philosophorum, all of which contain images of the alchemical hermaphrodite alongside other symbolic figures. In the Rosarium, a crowned hermaphrodite lying on a tomb represents the purified body awaiting the return of the soul, with descending figures and black crows encoding the stages of putrefaction and resurrection.

De Jong establishes the definitive identification: "The Hermaphrodite is the same as the Rebis, as is clear from the epigram of Emblem XXXVIII." A key passage from the Tractatus Aristotelis Alchymistae states: "Hence the Animated Stone is called Rebis, as it contains the perfection of everything: And it is called the Egg on account of its roundness, as it is spherical, or because it has the form and the depiction of the Macrocosm, which is spherical and contains all lower things." The Rebis thus connects to both the Philosophical Egg (Emblem VIII) and the cosmic geometry of Emblem XXI.

In Atalanta Fugiens, the Rebis appears most explicitly in three emblems. Emblem XXXIII depicts the Hermaphrodite resembling a dead person, lying in the dark, needing fire. The discourse explains that the Philosophers mean by "lying in the dark" the cold winter of putrefaction (nigredo), from which the Hermaphrodite must be brought first to whiteness (albedo) by increasing fire, then to redness (rubedo) by stronger fire. The transformation is framed as a sex change: the female nature (cold, moist) is converted into a powerful male nature (hot, dry) by the addition of warmth, and in this way a woman becomes a man, the volatile becomes fixed, and the imperfect becomes perfect.

Emblem XXXIV continues the theme: the Rebis is received in the bath (putrefaction in the dung), born in the sky (the white vapors rising to the top of the vessel), and having become red, strides over the waters. De Jong traces this to the Rosarium, which describes how conception takes place in the blackness at the bottom of the vessel while birth occurs in the white air at the top. Emblem XXXVIII presents the Hermaphrodite in yet another guise, with the epigram making the explicit identification with the Rebis.

The Rebis also connects to the serpent and dragon imagery in Atalanta Fugiens. De Jong cites the alchemical dictum that "the mountains supply serpents for the Rebis and the earth supplies sources," interpreting this as the contrast between sulphur-fire (mountains, dragons, heaven) and mercury-water (earth, springs), which together compose the hermaphroditic being. The reconciliation of these contrasts in the Rebis is the reconciliation of all the fundamental dualities in the cosmos.

Miner, writing about Blake and Atalanta Fugiens, notes that the Hermaphrodite of Emblem XXXIII and XXXIV influenced Blake's depictions of androgynous and dual-sexed figures, particularly in The Gates of Paradise. The calcination of the Rebis, framed by stylized flames and smoke, is described as both aesthetically pleasing and profoundly disruptive, capturing the alchemical conviction that destruction and creation are simultaneous.

In chemical terms, the Rebis concept maps onto the formation of stable chemical compounds from reactive elements. When two highly reactive substances combine to form a stable compound (as sodium and chlorine form stable sodium chloride), the resulting substance has properties fundamentally different from either component. The alchemists' insistence that the Rebis was neither male nor female but both at once reflects a genuine chemical insight about the emergent properties of compounds.

For the museum visitor, the Rebis is the alchemists' answer to the question of how opposites can coexist. It is the image of wholeness achieved through the integration of contrary forces, a concept that resonates far beyond the laboratory. In Maier's visual program, the two-headed, dual-sexed figure lying in darkness and awaiting the transforming fire is one of the most striking and memorable images in the entire sequence.

Meanings Across Registers

De Jong shows that alchemical terms operate simultaneously across material, medical, spiritual, and cosmological dimensions.

Alchemical

The 'two-thing': the hermaphroditic product of the coniunctio, uniting Sulphur and Mercury, Sol and Luna, into a single perfected substance.

Medical

The perfected balance of all contrary qualities in the body; the androgynous ideal of complete humoral equilibrium transcending any single temperament.

Spiritual

The integrated self in which all opposites—masculine and feminine, conscious and unconscious—are reconciled into a unified wholeness.

Cosmological

The cosmic androgyne; the primordial unity that preceded the differentiation of the elements, and to which the perfected cosmos returns.