The cipher was not a lock to keep secrets safe. It was a lock to keep women out.
The mysterious Voynich manuscript may contain medieval gynecological advice encrypted to restrict women's access to reproductive knowledge during the patriarchal late medieval period. Illustrations of women with objects near genitals and a complex 'rosette page' allegedly represent anatomical knowledge and conception, mirroring documented medieval censorship of sexual medicine.
- The Voynich Manuscript contains 240 pages acquired by antiquarian Wilfrid Voynich in 1912 and held at Yale University
- Researchers Keagan Brewer and Michelle Lewis propose the manuscript encrypts gynecological knowledge using a secret alphabet
- Johannes Hartlieb, a 15th-century Bavarian physician, created a cipher to hide contraceptive and abortifacient recipes from literate women
- The manuscript's 'rosette page' allegedly depicts the seven-chambered uterus and two vaginal openings as understood in medieval medicine
Researchers propose the 600-year-old Voynich manuscript contains hidden gynecological and sexual health information, with illustrations suggesting the author deliberately encrypted content to prevent women from reading it.
Six centuries after it was written, the Voynich Manuscript remains locked. Its 240 pages sit in Yale's vault, filled with an indecipherable script, impossible plants, naked women, and symbols no codebreaker—human or machine—has managed to crack since the American antiquarian Wilfrid Voynich acquired it in 1912. Now two researchers believe they have found the key not to the language itself, but to its purpose: the manuscript, they argue, is a deliberate encryption of gynecological and sexual knowledge, hidden not from enemies of the state but from women.
Keagan Brewer of Macquarie University in Australia and Michelle Lewis have published their theory in the journal Social History of Medicine, and it hinges on what the manuscript shows rather than what it says. Scattered throughout are illustrations of women holding objects near their genitals or pointing toward them—crude, explicit, and until now largely unexplained. The researchers propose that these images are not decorative but instructional, and that the manuscript's most elaborate illustration, the so-called rosette page, a six-page foldout with an intricate circular design at its center, depicts human conception and intercourse. The nine large circles within it, they argue, represent the seven chambers of the uterus as medieval physicians understood it, plus the two openings of the vagina—one external, one internal—that doctors of that era believed existed. The central circle, with its textured border, represents external anatomy; the smooth-edged circles around it represent the internal chambers.
What makes this theory cohere is the historical context Brewer and Lewis have assembled. In the late medieval period, medical texts dealing with gynecology and sexual health were routinely called "secrets of women," and they were routinely suppressed. The case of Johannes Hartlieb, a Bavarian physician who lived in the time and place the Voynich Manuscript was created, is instructive. Hartlieb was deeply anxious that increasingly literate women might read vernacular medical texts and use them to have premarital sex, to avoid pregnancy, or to end one. His solution was to invent a secret alphabet—a cipher—to hide recipes for contraceptives, abortifacients, and procedures that could cause infertility. He refused to write openly about postpartum vaginal salves, female sexual pleasure, the "correct" positions for conception, or changes in women's desire. The knowledge existed; the fear was that women would possess it.
The researchers found other examples of the same impulse across late medieval Europe. A 21-line encrypted text from northern Italy contained gynecological recipes, including one for abortion. A Bavarian manuscript had two entire pages erased—pages that had contained spells for invisibility and magical coercion of women. More commonly, censors simply blacked out or cut away specific words: genital terms, plant names in recipes, anatomical references. The pattern is unmistakable: information about women's bodies and women's sexuality was being actively hidden from women themselves.
If Brewer and Lewis are right, the Voynich Manuscript is not a cryptographic puzzle in the traditional sense—not a message from a spy, not a coded love letter, not a alchemical treatise. It is an act of patriarchal control disguised as incomprehensibility. The author encrypted gynecological and sexual knowledge not to protect it from theft or heresy charges, but to ensure that the women who might most benefit from it—women seeking to understand their own bodies, to manage their own fertility, to experience their own desire—could never read it. The cipher was not a lock to keep secrets safe. It was a lock to keep women out.
The theory does not explain every page of the manuscript, nor does it solve the underlying language question. But it offers something that centuries of cryptographic analysis have not: a coherent reason why someone would go to such elaborate trouble to make knowledge unreadable in the first place. It transforms the Voynich Manuscript from a curiosity into a document of suppression, and its incomprehensibility from a mystery into a strategy.
Notable Quotes
Our proposal aligns with the patriarchal culture of the era and resolves many of the manuscript's apparent contradictions— Keagan Brewer, in The Conversation
We found many examples of authors censoring themselves or readers destroying information in gynecological and sexual texts, often erasing only a few words—genital terms or plant names—but sometimes eliminating entire pages or chapters— Keagan Brewer
The Hearth Conversation Another angle on the story
Why would a medieval physician go through the trouble of inventing an entirely new alphabet just to hide medical information? Couldn't he simply refuse to write about it?
He could have, but that wasn't the anxiety. The anxiety was that the knowledge already existed—in Latin texts, in oral tradition, in the hands of midwives and healers. What Hartlieb feared was women reading it in their own language, in the vernacular. A secret alphabet made the information invisible to the literate women he was trying to exclude.
So the Voynich Manuscript might not be unsolvable at all. It might just be solved in a way that reveals something uncomfortable about medieval society.
Exactly. We've been asking the wrong question for six hundred years. We've been asking what the code means. We should have been asking why someone needed a code in the first place. The answer isn't cryptographic brilliance. It's fear.
Fear of what, specifically?
Fear that women with knowledge of their own bodies—how to prevent pregnancy, how to end one, how to experience pleasure—would use that knowledge to live differently than men wanted them to. The encryption wasn't about protecting the knowledge. It was about controlling who could access it.
If this theory is correct, does it change how we should think about the manuscript's value?
It transforms it from a puzzle into evidence. Not evidence of a secret code, but evidence of a secret agenda. The manuscript becomes a window into what medieval authorities were so desperate to hide that they invented an entire language to do it.