 It is not only for this terminological reason that Bolzano’s characterization of the ontological status of propositions and ideas remains in the last analysis nebulous and has therefore repeatedly evoked criticism. One must of course add, for the sake of doing justice to Bolzano, that no other advocate of such a World 3 — including Husserl, Popper and even Frege — has done better than he had done and has succeeded in saying anything clearer about this than what can already be found in Bolzano’s work. Despite all these deficiencies, Bolzano’s unproven assumption or postulation of propositions and ideas turned out to be extremely fruitful for his own research.