Tractus de Hermaphrodites

In Short

Giles Jacob’s Tractus de Hermaphrodites (1718) is an early Enlightenment treatise examining intersex conditions, ambiguous sexual anatomy, and unusual reproductive phenomena. Combining legal doctrine, natural philosophy, and colorful narrative vignettes, the work categorizes different anatomical variations, assesses how civil law governs their right to marry, and details scandalous intrigues involving "masculine females." It moves from legal and physical definitions to theoretical explanations of monstrous births and extraordinary conceptions. Lasting as a cultural artifact, it reveals how eighteenth-century society attempted to reconcile rigid legal frameworks and reproductive theories with the unruly realities of human biological diversity.

The Story

The treatise opens with a clear analytical ambition: to define sex, classify anatomical variations, and establish how the legal system ought to regulate individuals of a mixed nature. Jacob distinguishes between standard male and female biology—relying on classical humorology that deems females colder and more humid—before outlining five distinct categories of intersex individuals. For the author, the law must balance moral order with natural capability. He explains that civil law permits intersex individuals to choose a male or female role for matrimony based on whichever anatomy dominates. However, if they fail to perform according to that chosen role, they face severe legal penalties for sodomy. Jacob firmly dismisses popular myths that a single person could be fully functional as both sexes or engender a child entirely within themselves.

From legal definitions, the narrative shifts into dramatic, cautionary tales illustrating the "unnatural intrigues" of individuals who blur gender lines. Through elaborate romantic histories set in Italy, Jacob depicts women who use enlarged anatomy or artificial instruments to conduct affairs with other women. The central narrative follows two beautiful, aristocratic women, Theodora and Amaryllis, both thwarted in their traditional romances with men. Banding together in Ferrara, they turn to one another for comfort. Their domestic arrangement is upended when a male suitor, Philetus, disguises himself in female attire and paints his face to infiltrate their confidence. During an intimate encounter, he surreptitiously substitutes his own anatomy for an artificial device, surprising Theodora into a heterosexual union that ends in marriage.

Subsequent vignettes delve further into anatomical deception and its dangerous consequences, including a scene where a suitor named Diana attempts an uninvited encounter with a clergyman's wife, and another where a nobleman violently reacts upon discovering ambiguous anatomy in his partner.

In its final movement, the treatise transitions into natural philosophy and embryology. Jacob searches for the root causes of intersex births, monstrous physical deformities, and unusual pregnancies. He explores theories ranging from planetary influences and excess reproductive matter to the subtle actions of an internal "Intelligence" shaping the fetus in the womb. He rejects superstitious notions that demons or incubi can father children, insisting that demonic bodies are merely air. Instead, he grounds his conclusions in extraordinary medical cases, concluding with reports of stone-like abdominal masses retained for decades and claims of complex tissue growing within a man’s scrotum.

How It Unfolds

Mapping the law and the body The treatise begins by defining the biological distinctions between sexes and cataloging five specific types of intersex anatomy. It lays out how civil law allows individuals to select a marital role based on anatomical predominance while threatening harsh criminal penalties for non-performance.

The intrigues of Ferrara The narrative turns to illustrative romantic histories, detailing how two aristocratic women, Theodora and Amaryllis, unite after losing their male suitors. Their private companionate world becomes the backdrop for exploring romantic relationships between women.

The trickery of Philetus A suitor named Philetus disguises himself in women's clothing and cosmetics to gain access to Theodora's household. By deceiving her during an intimate moment, he forces a revelation that leads from artificial trickery to a traditional legal marriage.

Misadventures and violent discoveries A series of brief, chaotic episodes highlights the risks of ambiguous or deceptive anatomy, ranging from panicked alarms in a clergyman's household to a foreign Count who reacts with sudden violence upon detecting unexpected physical traits in his companion.

The mechanics of creation Jacob pivots to theoretical biology, evaluating how heat, moisture, and available embryonic matter cause physical deformities or intersex traits. He dismisses astrology and demonic incubi in favor of naturalistic explanations regarding fetal development.

Monsters and miraculous cases The book closes with documented medical anomalies, presenting historical accounts of animal-like infant births, a twenty-five-year abdominal stone mass, and a surgeon's report claiming to find bone and tissue inside a man's scrotum.

The People

• Theodora: A beautiful courtier’s daughter in Ferrara whose romantic hopes are crushed when her father banishes her suitor. She forms a tight bond with Amaryllis and engages in private intrigues, but she ultimately surrenders her non-traditional lifestyle to marry Philetus after discovering his true identity.
• Amaryllis: An educated merchant's daughter who flees to Ferrara after her lover, Sempronius, dies following a violent raid on her home. She seeks solace in a shared life with Theodora, navigating grief through intimate female companionship.
• Philetus: A determined suitor who uses elaborate trickery, women's clothing, and cosmetics to infiltrate Theodora and Amaryllis's household. He desires Theodora and uses deception to secure her hand in marriage.
• Leander: A Neapolitan youth of noble birth whose extravagant nature leads Theodora's mercenary father to reject him. His forced exile from Ferrara leaves him heart-broken, driving him to an early grave.
• Isabella: An adventurous figure in Urbino whose late-night encounter with a foreign Count ends in tragedy when her partner reacts with horrific violence upon discovering her physical ambiguity.

In Its Own Voice

"For the Definition of the Word Sex, it is no other than a Distinction of Male and Female, in which this is most observable, that for the Parts of the Body, there is but little Difference between them..."

Jacob sets out his underlying physical framework, asserting that the baseline physical structures of men and women share fundamental similarities.

"I am perswaded there will not be one single HERMAPHRODITE the more in the World, on account of the publishing this TREATISE."

In his preface, the author defends his motives against contemporary critics, framing his work as innocent entertainment rather than an encouragement to vice.

"The Clitoris in Women suffers erection and falling in the same manner as the Penis in Men..."

Discussing anatomical specifics, Jacob explains the physiological mechanisms that he claims drive both desire and physical capacity in human intimacy.

What It's Really About

At its core, Tractus de Hermaphrodites is about eighteenth-century anxieties surrounding the stability of human categorization. It explores the friction between rigid legal and social categories—such as marriage, sodomy laws, and binary gender roles—and the unpredictable variations of human anatomy. The book wrestles with the boundaries between natural order and monstrous deviation, asking whether unusual physical traits stem from divine intent, maternal imagination, or simple mechanical errors in embryonic material. Beneath its sensational stories of deceitful suitors and secretive courtships lies a genuine attempt to understand the limits of biological generation, questioning whether reproductive matter requires both sexes or if one sex carries the primary blueprint of life.

Why Read It Today

Modern readers interested in the histories of gender, medicine, and sexuality will find Tractus de Hermaphrodites a fascinating, if jarring, window into the early Enlightenment mind. It offers a rare glimpse into how pre-modern legal systems and medical theorists attempted to classify intersex bodies without the benefit of modern genetics or endocrinology. Reading it feels like browsing a period cabinet of curiosities, where dry legal analysis abruptly gives way to dramatic romantic novellas, street violence, and medical marvels.

The text presents several reading hurdles typical of its era. Readers must navigate archaic medical theories—such as humors, cold maternal warmth, and maternal impression—alongside period moralizing and explicit non-consensual deceptions within the narrative sections. The prose carries eighteenth-century capitalization and rambling sentence structures, and the tone swings wildly between formal legal commentary and lurid storytelling. Nevertheless, what remains with the reader is a striking realization of how persistently human culture has struggled to define, regulate, and comprehend bodies that defy simple categorization.