Book excerpt: This volume reveals new insights on the faculty of language. By proposing a new approach in the analysis and description of Italian Sign Language (LIS), that can be extended also to other sign languages, this book also enlightens some aspects of spoken languages, which were often overlooked in the past and only recently have been brought to the fore and described. First, the study of face-to-face communication leads to a revision of the traditional dichotomy between linguistic and enacted, to develop a new approach to embodied language (Kendon, 2004). Second, all structures of language take on a sociolinguistic and pragmatic meaning, as proposed by cognitive semantics, which considers it impossible to trace a separation between purely linguistic and extralinguistic knowledge. Finally, if speech from the point of view of its materiality is variable, fragile, and non-segmentable (i.e. not systematically discrete), also signs are not always segmentable into discrete, invariable and meaningless units. This then calls into question some of the properties traditionally associated with human languages in general, notably that of 'duality of patterning'. These are only some of the main issues you will find in this volume that has no parallel both in sign and in spoken languages linguistic research.