An attempt at clarifying the conditions which make communication possible. The central methodological notion is that of 'parlare comune' (an approximate translation is 'common speech'). On the basis of an analysis of examples, R. deals with the operation and the limitations of common speech, on an interdisciplinary basis, and at all levels of discourse. Meaning and communication are seen as social practice; the linguistic and non-linguistic context of messages is always taken into account. Further conceptual instruments like 'universe of discourse', 'language game ', 'initial and additional meaning' are used. The book has two appendices, one of which contains a criticism of Husserl's notion of intentionality as a prerequisite for human communication.