 A related phenomenon is exhibited by ‘John danced if Mary sang and Chris slept’. Is the intended proposition of the form ‘(A if B) and C’ or ‘A if (B and C)’? Indeed, it seems that the relation between word-strings and propositions expressed is often one-to-many. Is someone who says ‘The artist drew a club’ talking about a sketch or a card game? One can use ‘is’ to express identity, as in ‘Hesperus is the planet Venus’; but in ‘Hesperus is bright’, ‘is’ indicates predication. In ‘Hesperus is a planet’, ‘a’ seems to be logically inert; yet in ‘John saw a planet’, ‘a’ seems to indicate existential quantification: \(\exists x [P(x) \land S(j, x)]\). (One can render ‘Hesperus is a planet’ as ‘\(\exists x [P(x) \land h = x]\)’. But this treats ‘is a planet’ as importantly different than ‘is bright’; and this leads to other difficulties.) According to Frege, such ambiguities provide further evidence that natural language is not suited to the task of representing propositions and inferential relations perspicuously. (Leibniz and others had envisioned a “Characteristica Universalis”, but without detailed proposals for how to proceed beyond syllogistic logic in creating one.) This is not to deny that natural language is well suited for other purposes, perhaps including efficient human communication. And Frege held that we often do use natural language to express propositions. But he suggested that natural language is like the eye, whereas a good formal language is like a microscope that reveals structure not otherwise observable. On this view, the logical form of a proposition is made manifest by the structure of a sentence in an ideal formal language—what Frege called a Begriffsschrift (concept-script); where the sentences of such a language exhibit function-argument structures that differ in kind from the grammatical structures exhibited by the sentences we use in ordinary communication.