In line with the Defining Matrix Analysis model he is devlopping since 1994 the author studies a function of the supports that interfaces syntax, lexicon and semantics. Every perceived utterance hides another one, necessarily more analytic and comprising all the predicate "realizers", including supports. The hidden utterance is what the speaker intends or what the hearer understands. Givent this assumption, one can say that almost any predicate is by nature a dual one and that this feature is a defining property of natural languages that helps explain many contradictory issues about languages; namely their evolution, their origin, their acquisition and, most of all, how meaning is built withe heterogeneous and irregular lexical, syntactic and semantic material. After examining somme apparent problems raised by this duality the author suggests a frame for a typology of predicates that allows to deal sucessfully wiht these problems