Frege developed his original theory of meaning in early works like Begriffsschrift (concept script) of 1879 and Grundlagen (foundations of arithmetic) of 1884. On this theory, the meaning of a complete sentence consists in its being true or false,[5] and the meaning of each significant expression in the sentence is an extralinguistic entity which Frege called its Bedeutung, literally meaning or significance, but rendered by Frege's translators as reference, referent, 'Meaning', nominatum, etc. Frege supposed that some parts of speech are complete by themselves, and are analogous to the arguments of a mathematical function, but that other parts are incomplete, and contain an empty place, by analogy with the function itself.[6] Thus "Caesar conquered Gaul" divides into the complete term "Caesar", whose reference is Caesar himself, and the incomplete term "—conquered Gaul", whose reference is a concept.