Abstract
Nothing is as complex as the world – but soon we must master this complexity to be able to live in it. Our means to do so are the languages. However, they are so manifold and so differently in vocabulary, structure and in the way linked with the world that it is difficult to ascribe to them a common relation. Noam Chomsky’s empirical search for a deep structure grammar had no success. For Leibniz our actual world is infinitely complex, beginning with the monad and its subordinated “worlds in the worlds”. Thus exactly our problem constellation of today can already be found there–namely how to master infinite complexity by languages. But what connects these languages? This will be discussed from (1) the representational function of signs concerning the connection between res / signum / notio / idea, via (2) the Ars characteristica and its formal-linguistic sign systems; the next step counts (3) for the natural languages and their functions, marked above all by an adaptation to new problems. The last step deals with the functions of languages, finally leading to the unity of reason.