An exploration of secret languages, moving among hermetic artificial tongues as diverse as criminal jargons and divine speech. 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. The first recorded jargons date to the time of the Renaissance, when writers across Europe noted that obscure languages had suddenly come into use. A varied cast of characters-lawyers, grammarians, and theologians-denounced these new forms