 We here distinguish between propositions [Aussagen] and assertions [Sätze]. An assertion is the affirmation of a proposition. A mathematical proposition expresses a certain expectation. For example, the proposition, “Euler’s constant \(C\) is rational”, expresses the expectation that we could find two integers \(a\) and \(b\) such that \(C = a / b\). Perhaps the word “intention”, coined by the phenomenologists, expresses even better what is meant here … The affirmation of a proposition means the fulfillment of an intention. (Heyting 1931: 113 [Benacerraf &amp; Putnam 1983: 58–59])