Cipher methods Symbols
Lingua Ignota (Hildegard of Bingen, 12th c.)
The Lingua Ignota (‘unknown language’ in Latin) is a constructed language invented by Hildegard of Bingen (1098-1179), Rhineland Benedictine abbess, composer, mystic, herbalist and theologian. Documented in her Riesencodex (‘Giant Codex’, written c. 1170-1175 and kept at the Hessische Landesbibliothek in Wiesbaden), it consists of a 1011-word lexicon (the Litterae Ignotae) and an alphabet of 23 letters (the graphic Litterae Ignotae).
Linguists consider Lingua Ignota to be one of the oldest documented constructed writing systems in Western history, older than Tolkien’s languages (20th c.) and even the Renaissance Masonic Lingua Ignota. Its exact status remains debated: practical language for the convent sisters? Mystical code reserved for Hildegard and her secretary Volmar? Pure Christian glossolalia exercise? Hildegard’s words in the Vita Sanctae Hildegardis claim a divine inspiration, which does not detract from the linguistic sophistication of the system.
How does the alphabet work?
The cipher uses a monoalphabetic substitution: every letter of the plaintext is replaced by a glyph drawn from a fixed correspondence table. It is one of the oldest cryptographic techniques on record — already described in antiquity (Caesar cipher, ~50 BC) — and the most directly readable family for a beginner.
The table has 24 glyphs for the 26 Latin letters: J folds onto I and V folds onto U (medieval Latin alphabet before these two modern letters). No digits.
Cryptographic strength: weak. Because every plaintext letter always maps to the same glyph, the cipher falls to a frequency analysis in a few dozen words (in both English and French, E remains the most common letter, an immediate entry point). Monoalphabetic substitutions are therefore used today for their decorative, playful or pedagogical value — not to protect real information.
Historical and modern usage
- Riesencodex (c. 1175) — original manuscript, Hessische Landesbibliothek Wiesbaden.
- Medieval studies — studied as the first Western constructed language in medieval-history curricula.
- Hildegard community — Hildegardian writings revived after her formal canonisation (2012) and her declaration as Doctor of the Church (2012) by Benedict XVI.
- Pedagogy — gateway to historical constructed alphabets in linguistics curricula.
Related variants
- Theban (Honorius of Thebes) — another medieval mystical alphabet, see our entry.
- Enochian (Dee/Kelley, 16th c.) — see our entry, a later ‘revealed’ alphabet.
What are the weaknesses?
- Monoalphabetic substitution — immediate frequency analysis.
- Documented alphabet — public table reproduced since the 19th-c. critical editions of the Riesencodex.
- J→I, V→U folds — information loss: IUSTE and JUSTE cannot be distinguished after encryption.
The 24 glyphs
