 Although Bolzano took propositions to be composed of parts, which he called ideas, he does not offer a definition of the concept of a proposition as a certain kind of structured whole. The reason for this was that no definition he had found in the writings of others, nor any that he could think of himself, was satisfactory. Instead, he seeks to convey what he means by ‘proposition’ using the procedure he had earlier called ‘circumscription’ (cf. TS, §668, no. 9), presenting the reader with a number of sentences containing the word that are supposed to be true when it is rightly understood.