The first is the composition of a sentence from its parts. A sentence consistsof its parts in a straightforward sense: The concatenation of a noun phraseand a verb phrase simply is a sentence, just as a top set upon four legssimply is a table; the table is not something other than the top set uponthe legs, and the sentence is not something other than the noun phraseconcatenated with the verb phrase. The second model is the application of afunction to an argument. The result of applying a function to an argumentis not (normally) a complex consisting of the function and the argument.It is, rather, the value of the function for that argument. This model ofcomposition is the one Frege ultimately applies in the realm of reference:A concept is a function from objects to truth-values, and the reference ofa (non-embedded) sentence is its truth-value; “Frege had a beard” refers tothe truth-value that is the result of applying the ‘concept-function’ denotedby the predicate to the object denoted by the subject.