<P>In <I>Dark Tongues</I>, Daniel Heller-Roazen offers a sustainedexploration of a perplexing fact that has never received the attention it deserves. Wherever humanbeings share a language, they also strive to make from it something new: a cryptic idiom that willallow them to communicate in secrecy. Secret languages may be playful or serious, as apparentlyimpenetrable as a foreign tongue, or only slightly different from the languages from which theyspring.</P><P>The first recorded jargons date to the time of the Renaissance in Europe.A varied cast of characters -- lawyers, grammarians, and theologians -- denounced these new forms ofspeech, arguing that they served a single and illegitimate end: crime, plotted in tongues thathonest people could not understand. Before this, in epochs and regions as diverse as archaic Greeceand Rome, medieval Provence and Scandinavia, singers and scribes also invented opaque varieties ofspeech, not to defraud but to reveal and record a divine thing: the language of the gods, whichpoets and priests alone were said to know. </P><P> <I>Dark Tongues</I> movesamong these hermetic artificial tongues, exploring phenomena as diverse as criminal jargons anddivine speech, Saussure's and Tristan Tzara's work of anagrams, Jakobson's theory of subliminalpoetic patterning, and the secret writing systems of the Biblical copyists and Druids. In its elevensuccinct chapters, Dark Tongues advances a single thesis: that such willfully obscure languages allrest on poetic techniques, which work to play sound and sense against each other.</P>