 For Montague the principle of compositionality did not seem to be a subject of deliberation or discussion, but the only way to proceed. In effect he made compositionality the core part of his ‘theory of meaning’ (Montague 1970c, 378), which was later summed up in the slogan: ‘Syntax is an algebra, semantics is an algebra, and meaning is a homomorphism between them’ (Janssen 1983, 25). Yet although Montague used the term ‘Frege’s functionality principle’ for the way in which extension and intension are compositionally intertwined, he did not have a special term for compositionality in general. Later authors, who identified the Principle of Compositionality as a cornerstone of Montague’s work, also used the term ‘Frege’s Principle’ (originating with Cresswell 1973, 75); Thomason 1980 is an early source for the term ‘compositional’.