As a result of the exclusion of subjective psychological concepts as well as of the objective meanings of words, the direct relationship between signs and what they stand for came clearly to the fore. In the Tractatus Wittgenstein has investigated this relation in detail, and has drawn attention to its essential features.¹ In speaking of it, he uses the German verb abbilden, the literal translation of which is "to picture", "to depict". He calls a sentence a picture (Bild), because he wants to compare it with a broad spectrum of other examples of pictures, ranging from a tableau vivant (lebendes Bild: a silent and motionless group of persons, etc., arranged to represent a scene) to a mathematical projection (Abbildung).² For our own terminology we prefer the more neutral term "representation" We want to give it a broader meaning so that it covers not only Wittgenstein's picturing-relation, but also the corresponding semantical relations in Russell, Carnap, etc.