Dark Tongues constitutes a sustained exploration of a perplexing fact that has never received the attention it deserves. Wherever human beings share a language, they also strive to make from it something new: a cryptic idiom, built from the grammar that they know, which will allow them to communicate in secrecy. Such hidden languages come in many shapes. They may be playful or serious, children’s games or adults’ work. They may be as impenetrable as foreign tongues, or slightly different from the idioms from which they spring, or barely perceptible, their existence being the subject of uncertain, even unlikely, suppositions.

It was in the Renaissance that writers across Europe first noted that willfully obscure languages had come into use. A varied cast of characters — lawyers, grammarians, and theologians — denounced these new forms of speech, arguing that they were tools of crime, plotted in tongues that honest people could not understand.

Before the emergence of these modern jargons, however, the artificial twisting of languages served a different purpose. In epochs and regions as diverse as archaic Greece and Rome and medieval Provence and Scandinavia, singers and scribes also invented opaque varieties of speech. They did so not to defraud, but to reveal and record a divine thing: the language of the gods, which poets and priests alone were said to master.

Dark Tongues moves among these various artificial and hermetic tongues. From criminal jargons to sacred idioms, from Saussure’s work on anagrams to Jakobson’s theory of subliminal patterns in poetry, from the arcane arts of the Druids and Biblical copyists to the secret procedure that Tristan Tzara, founder of Dada, believed he had uncovered in Villon’s songs and ballads, Dark Tongues explores the common crafts of rogues and riddlers, which play sound and sense against each other.

Caroline Walker Bynum is professor emerita of medieval European history at the Institute for Advanced Study and University Professor Emerita at Columbia University. She studies the religious ideas and practices of the European Middle Ages from late antiquity to the sixteenth century. In the 1980s, she worked on women’s spirituality in Europe; in the 1990s, she turned to the history of the body. Her recent work, Wonderful Blood (2007) and Christian Materiality (2011), locates the upsurge of new forms of art and devotion in the fourteenth and fifteenth centuries against the background of changes in natural philosophy and theology and reinterprets the nature of Christianity on the eve of the reformations of the sixteenth century. Her essays “In Praise of Fragments” (in Fragmentation and Redemption), “Why All the Fuss About the Body?” (in Critical Inquiry and reprinted in The Resurrection of the Body, expanded edition, 2017), and “Wonder” (in Metamorphosis and Identity) are widely cited as discussions of historical method. Bynum has taught at Harvard, the University of Washington in Seattle, and Columbia University. She was a MacArthur Fellow from 1986 to 1991 and has won the Ralph Waldo Emerson Prize of Phi Beta Kappa, the Jacques Barzun Prize of the American Philosophical Society, the Gründler Prize in Medieval Studies, and the Haskins Medal of the Medieval Academy of America. She has won three undergraduate teaching awards, one from the University of Washington and two from Columbia University. She is a past president of the Medieval Academy of America and the American Historical Association, a member of the American Academy of Arts and Sciences, the American Philosophical Society, and the Orden Pour le Mérite für Wissenschaften und Künste of the Federal Republic of Germany, and a Fellow of the Medieval Academy of America and the British Academy.